Game Breaker/The Elder Scrolls

Arena

 * The Healer class was considered by many the best in the game, and for a good reason – while only using the second best level of armor, and only concussion weapons, he enjoys a considerable discount in the cost of restoration spells. Among the restoration spells, there are fortify attribute spells, the absorb magic spells, and above all else, the powerful shield spell- the basic version “Will create an invisible shield around the caster, which will absorb 15 points of damage, plus an additional 5 points for every level of the caster before being dissipated.” The detail is that there's no duration for this effect, it will simply last until the caster receives enough damage. You can go to the Mage's guild, create an optimized version of the spell that uses all your magicka, go to the inn, cast the spell, rest, and then go to the dungeons with a few extra hundred HP.
 * You can easily spellmake a version of the reflect spell to give you 100% spell reflection as early as level SIX. It's a little costly, but if you increase the duration you can easily run around dungeons while watching enemies with magic attacks suicide themselves on you. If you need more magicka you can do the same with Spell Absorption.

Daggerfall

 * The Elder Scrolls: Daggerfall suffered from ridiculous balance issues. On one end of the scale, being a thief makes the game ridiculously difficult, which is the only way to cripple your character. On the other extreme, the entire world is offered to you on a silver platter to break as you like, including:
 * Getting loans from a bank. Banks give out loans to a maximum of [Player Level x 50,000] gold, with no collateral required up front. There are 43 provinces, and each one is completely independent of each other, and only 3 are actually essential to the plot. Take out a loan from some banks out in the boondocks when you're level 3, and go off and buy yourself a house in your home province. You'll never feel the repercussions, and even if you did return to the boondocks, the guards will never arrest you for it. This says nothing of what you can do if you decide to take out the loans at level 10 instead.
 * The Unlock spell doesn't check lock strength when the player is in an outdoor area, so you can cast a 1% Chance Unlock spell and it'll always work on any door if you're outdoors. Combine that with how shoplifting is possible by just walking into a shop after hours, and you can rob the entire city blind. All shops restock every day. This makes it easy to make hundreds of thousands of gold in only a few real life hours of work.
 * The player is given the SpellMaker ability immediately after joining the Mage's Guild. Spells are formed with incrementing formulas: for example, Spell Damage is [X + Y(per level)]. The player can make a nuke spell with damage of [1 + 15(per level)], meaning that if the player is level 6, the nuke will do 90 damage per shot (enough to kill anything that breathes), yet still have a reasonable casting cost.
 * The player's attack speed is determined by the Speed stat. Increase it to 100, and monsters literally cannot melee you. You'll swing fast enough that they'll always get knocked back out of range.
 * The Character Creation is far more flexible than in the game's sequels. A character can choose permanent spell absorption from the start of the game, as well as a bunch of other super-powered abilities, with no drawbacks if the player decides (although it'll take longer to level up if the player only stacks good attributes). Create a spellcaster with permanent spell absorption, SpellMake an area-affecting nuke and cast it wherever you go. As long as the nuke hits you, you'll regenerate the spell points back and can cast it immediately again; you can chain-nuke your way through any monster in the game. Note also that spell-casting is instantaneous, so if your fingers don't get tired, you can cast a permanent everything-destroying nuke forcefield around yourself as you explore a dungeon. (Sometimes the spell absorption breaks itself and you stop absorbing anything, leading to a horrifying suicide.)
 * Furthermore, if the player enchants an item with a casting skill bonus that raises said skill over 100, spells associated with that particular magic can become several magnitudes more powerful. Simply breaking the regular one-hundred skill maximum, the player is capable of crafting a spell that deals hundreds or even thousands of points of damage all with a cost of 5 MP or less (usually 1-5% of total MP).
 * The Ring of Hircine. Normally, a werewolf character has to murder at least one civilian per month or suffer a massive stat and health penalty. However, with the ring, not only is this disadvantage nullified, but you get to keep all the bonuses of being a werewolf with literally none of the drawbacks (so long as you remember not to shift when in public, of course). And to top it all off, getting the Ring is fairly simple once you know where to find a Witch or Warlock Coven and have the necessary funds.

Morrowind

 * The game The Elder Scrolls: Morrowind contained an Item Crafting system that allowed the player to easily unbalance the game by producing weapons with extremely high bonus damage or by buffing character stats to absurdly high levels. A popular video circulated shows a player completing the game's main quest in less than half an hour by using the alchemy skill to buff key stats into the thousands (from a normal range of 1-100).
 * There are a couple of other videos out there that abuse other game breaking item combinations available right at the start in order to finish the main quest in under 10 minutes.
 * Boosting one's intelligence in this manner can produce similar results. As the magnitude increases each time around, one can easily skyrocket to over 200 MILLION intelligence, then create obscene Restore Health/Fortify Attack/Spell Absorption with durations that would last for MONTHS of real-time play. Yes, Morrowind allows you to reach The Singularity.
 * Custom made 'Fortify Skill' spells could get really powerful. Without the expansions it took a long, tedious and somewhat hidden quest to get the spell effect but with the first expansions it was readily available. 'Fortify skill by 100 points for 1 second' spells were cheap enough and with many skills (Enchant, Alchemy, Mercantile, Speechcraft, Armorer, Security) one second (or three for Security) was all you needed. Fortifying your magic skills to get a single powerful spell off might also be useful and 'Fortify Sneak' was at least useful for stealing.
 * Also, there is a man in the first expansion that sells the otherwise extremely rare Grand Soul Gems. Because even the weakest soul trapped in these will sell for far more than the cost of the gem, and they can also hold Golden Saint souls, which can be used to create powerful enchantments (like... summoning Golden Saints!), the resulting cycle gives the player unlimited amounts of money and enchantments.
 * 'Cast when used' enchanted items can potentially be huge game breakers, because they have zero casting time, meaning you can re-cast a spell as fast as you can click the mouse. Even if your enchantment spell only does about 10 points of damage you can cast it 5-10 times each second and kill enemies almost instantly.
 * By picking up a modest amount of Absorb Magicka (from birth sign) and then stacking Sanctuary on enchanted items, you will be Nigh Invulnerable. At about 75 Sanctuary, nearly every melee attack will miss and spells cast upon you will have a low chance of hitting. Plus that is before any spell resistance you may have from racial abilities or enchantments.
 * Invisibility will make enemies ignore you completely, but ends when you attack or interact with anything. However, if you enchant a ring with constant effect invisibility, you can instantly re-apply the effect at any time and at no cost by removing and re-equipping the ring. Naturally, this can be abused disgustingly.
 * Or better yet, 100% chameleon. Enemies can't see you and you can do anything you like without worrying about recasting the spell.
 * If you have the Tribunal expansion, you can  If you managed to do that, you can loot the best defensive item in the game: A ring with 100% Reflect, 100% Resist Magicka, 100% Resist Paralysis, AND health and fatigue restoration. Note that all of this effect are constant. Couple it with homemade enchated items/spells and you will be pretty much Nigh Invulnerable.
 * For a broken but somewhat less abusive mechanic, players could offer a very, very low price on any transaction to a dealer. The player would suffer a small hit to their reputation with that character each time they failed, but that reputation was restored and increased one point for completing the transaction. Since there was always a chance in hell of getting it, mash the button. Clean out a mage's stock for the cost of a third of his stuff.
 * Lampshaded in Skyrim's in-game book "The Buying Game," which stated the "Buying Game" could be "broken" by offering "insultingly low offers."

Oblivion

 * In The Elder Scrolls: Oblivion, the player can craft five pieces of armor which each have the "Chameleon 20%" enchantment. Since spell effects stack, equipping them all results in the player being completely invisible. The way the game is coded makes it so that enemies can't intentionally attack the player no matter what, making the player almost immortal. This leads to the game actually becoming slightly broken, as certain NPC interactions disregard the player's undetectable state, making for some very odd inconsistencies. If the player considers Bribing Your Way to Victory, then they can purchase an add-on which allows them to obtain this armor at level 1.
 * Capturing a daedric Sigil Stone yields a potent enchantment a character can use to empower a previously mundane item. The enchantment provided is random. While pursuing the main quest, if one saves one's game before grabbing a Sigil Stone, one can reload, and reload, until one gets a stone proving as specific enchantment one wants.
 * And that is just the tip of the iceberg. The game allows you to collect a set of items which give you 100% invulnerability to magic and melee damage, pretty much 90% of all the damage your character will take and the remaining 10% of ranged attacks can simply be dodged. Then there is the abilty to make your own spells, which allow you to become a godlike craftsman, negotiator, or alchemist for a few seconds, but that is all you need, as doing any of these things pauses the timer on the spell. Then there is weakness stacking; make a weapon with a mere 10 points of magical elemental damage, 100% vulnerability to this damage, and 100% vulnerability to magic in general again for a few seconds only. On every consecutive strike on a target the amount of damage, and the vulnerability to this damage will be in increased. 6 hits will kill any creature. And before a patch, you could do this on yourself for ridiculously strong buffs.
 * Clarifying this for those not familiar with the game: your first strike would make your opponents doubly vulnerable to magic (100% from the spell effect + base 100% susceptibility). "Weakness to magic" is a magical effect, so your second strike would be doubly effective, inflicting another 200% vulnerability for a total of 400%. And so on, with each strike doubling your opponent's susceptibility to magic. Absolutely nothing in the game has a snowball's chance in Hell of contending with this.
 * A more potent version of the damage and magic immunity effects is reflect, no further explanation should be required as to what that entails. It is possible to run up to loads of enemies or monsters, then simply stand there and go AFK to get a coffee while they kill themselves attacking you.
 * To elaborate further upon this: the AI is not smart enough to realize not to attack someone with 100% reflect damage, or not to cast spells on someone with 100% reflect spell. The result is that no one is able to affect you in any way.
 * Oblivion is also susceptible to a sneaky route to infinite power for players who want to get some time away from the keyboard. Get your willpower high enough so that you can recover one point of MP faster than it takes you to cast a spell. Design a really weak restoration spell that only costs one point of MP. Then hold your cast button down with a heavy object or tape or something, situate your character in the corner of some room where he's safe, turn off the monitor, and go find something else to do for six or so hours. When you come back, you should have amassed incredible skill with the school of magic that does buff spells as well as levelled up, and can soon design and cast buff spells that send your stats into the gazillions. Game stomping commences. It's like how Rock Lee would become a great mage if he were an Elder Scrolls character: "If I cannot cast 100 Boost Healths now, then I have to do 200 Boost Lucks!"
 * Doesn't work as well as it used to in Morrowind, though, because the game is hardcoded not to allow stat values above 255.
 * Additionally, by casting enough custom spells like "buff my Magika & Intellect by the maximum valuable allowed, for 120 seconds" to give yourself ridiculous amounts of magika, then casting enough equivalent "boost my willpower" spells, magika regenerates so quickly and you have so much of it that you don't even need to bother with keeping potions around. (Regen does not occurs if you have selected the Antronarch birthsign.)
 * Something very similar is possible with sneak and athletics merely by leaving your character running/sneaking in place in an inside corner of a safe building. Somewhat less of a cheat since these skills take a long time to level normally.
 * Magical skills are stupidly easy to increase once you get access to a spellmaking altar; this entails either progress in the Mages' Guild or building one in the Frostcrag Spire DLC. Either way, the idea is to make silly training spells all set to the minimum settings--"Light 3 feet for 1 second on self", "Damage Fatigue 3 pts. for 1 second on self", and so on. Skill increases depend only on the action, not on the actual difficulty of the action; for example, punching a mudcrab gives the same amount of Hand-to-Hand training as punching a guardsman, and more relevant to our case, casting "Summon Skeleton for 1 second" gives the same amount of Conjuration training as "Summon Skeleton for 60 seconds". However, spells need to actually affect a target to count for skill experience, hence the "on self" part. The end result, at any rate, is a spammable spell whose magicka cost is trivial due to magicka regeneration rate (and most characters that don't regenerate magicka will just absorb their own spell anyway). As you walk around town, feel free to set yourself on fire or summon spontaneous skeletons; the NPCs don't care if you assault yourself. Besides, that fatigue will also regenerate itself without any effort whatsoever, meaning that the only visible result of the spell is experience in the skill. If the magic is also one of your major skills, say hello to ridiculous level gains!
 * Magic in Oblivion:
 * The Spellmaking Altar lets you create custom spells As long as you have a spell you can use, you can make customs spells with that spell's effect with any variation of range, area of effect, target, intensity and time of effect you want, even if the original spell didn't have it(barring cost of creating spell and Magicka cost, of course). For example, you start with the Flare spell, a basic Fire Damage spell that does a measly 6 pts. of damage. With that spell, you can make, for example, a Fire spell that does 6 pts. of damage per second for 10 seconds. If you add to it Weakness To Fire at 100% for 10 seconds, the next spell does 12 PTS. PER SECOND. You can join together pretty much every effect you can think off for some truly staggering magical effects.
 * Custom spells can have diverse magical effects instead of just one specific effect, which can allow you to make very flexible, multi-use spells. For example, you could make a Fire Damage spell that does, say, 45 pts. of damage, but if an enemy is resistant to fire, you just wasted magic points on an attack that's useless. However, if you make the spell do 15 pts. each of Fire, Frost and Shock, you'd still do 45 pts. of damage, but divided in three different damage types: the enemy that was resistant to Fire would still be smacked by the other two effects for 30 pts. of damage. Also, any custom spells have the speed of THE FASTEST MAGIC TYPE USED TO CREATE THE SPELL. For example, you could make a massive damage, long range Fire spell, but add one measly point of Shock damage. This would make the spell come out as an almost-instantaneous bolt instead of a slow-moving fireball, but STILL deliver the full Fire damage. Finally, triple elemental spells are actually cheaper to cast than single element spells.
 * Although not entirely Game Breaking, it is possible to make a legitimate One Hit KO skill. A player with 100 Destruction skill can make a spell to do 100 Fire, 100 Frost, 100 Shock, and 100 Magic Damage on touch for exactly 250 Magicka. Although that's costly, it will basically kill anything and everything in one hit, and its use of every element makes it work around most enemy resistances.
 * Drain Health spells. Drain Health damages your opponent's health BUT ONLY TEMPORARILY. For example "Drain Health 10 pts. for 5 secs." means the attack does 10 points of damage, but after the 5 seconds pass, the health comes back, which to one with normal logic faculties sounds like a bum deal. HOWEVER, if an enemy has less HP than what the attack drains, it's an instant kill. By doing the Mages Guild quest and getting access to a Spellmaking Altar, you can make an Apprentice Level Drain Health spell that does 100 HP of damage for 1 second on touch... which will kill pretty much any lesser Daedra instantly, and which would easily kill most humanoid foes after just hitting them a few times with any weapon. This spell costs a measly 32 Magicka to cast.
 * There's not a single spell in the game you cannot make more effective simply by making it yourself. For example, suppose you see a Fire Damage spell that does 25 points of damage on touch. You can make a 5 damage x 5 seconds spell(same damage, but over a few seconds instead of instantly) and it'll be MUCH cheaper to cast. Using tweaks like this to your advantage, you can make OBSCENELY powerful spells for cheap casting costs.
 * Some spells you acquire from vendors or quests do provide a magicka cost discount over making the same spell at the altar, although these are rare. For example, Wizard's Fury is given to the player in the course of the Mage's Guild questline, it is a triple-elemental projectile that is more that 50% cheaper to use than a player-made spell with the same properties. It is a great ranged attack.
 * You can make Weakness to X spells, where X equals a damage type(Fire, Frost or Shock). If you do the spell at 100%, any spell or damage done with a weapon enchanted with X type of damage doubles in strength for the duration of the spell. If you add Weakness to Magic 100%, damage QUADRUPLES.
 * It gets worse. Create a spell called Weak A, weakness to Fire/Frost/Shock/Magic at 100%. Create another spell called Weak B, with the exact same effects. Since the names are different they stack. Toggle between these two a couple of times and you can one shot anything in the game.
 * How could anyone forget the legendary chain spells? All you need to do is create any old spell (healing, lightning, etc.) and then add a fortify magicka spell of a greater power than the spell cost for 3 seconds (time it takes to cast a spell). Thus, one gets the power to continuously use a spell for as long as they keep casting the spell (woe unto their magicka meter once they stop casting, as it will go to zero).
 * If you do the Daedric Quest for Azura, you get Azura's Star, a reusable Grand Soul Gem. Go to an Enchanting Altar and you have just created a nuke factory and a money-printing machine in one. Simply do the folowing: have a weapon or spell that does Soul Trap; kill an enemy while grabbing their soul; take any piece of crap equipment you can get your hands on, enchant it and sell it. Lather, rinse, repeat. You can make equipment that's THOUSANDS of times its original value just by enchanting it, no matter how measly or useless the enchantment is.
 * In some versions, anyway. Altars of Enchantment were tweaked so the expense of enchanting an item perfectly matches the value of the item created for later versions of Oblivion.
 * Enchanting a weapon, no matter how puny the enchantment is, instantly makes it a weapon usable against non-corporeal beings. This even applies if the weapon DOES NOT HAVE A CHARGE. Also, if you enchant a weapon with X damage type and use a Weakness to X 100% spell on the enemy, the weapon will hit with the enhanced damage EVEN IF THE WEAPON DOES NOT HAVE A CHARGE. It is MUCH easier and cheaper to recharge your magic points than to recharge a weapon, so this results in a weapon that always does monstrous damage if you have the spell to set it up beforehand.
 * Have fun with the gamebreaking 100% reflect damage suit (not a personal enchantment, but can be obtained using named items and sigil stones). This means all melee attacks fail to damage you. AT ALL. While hitting the attacker for EXACTLY as much as you would have taken. Now, after this you design a "Counterspell" spell: Reflect Magic 100% for 1 second. Takes 12 magika to cast. If you see someone raise their hand, cast the spell, and watch as the spell bounces back to the squishy mage. With these, you can't take melee or magic damage, while reflecting it all. so all the game can do is shoot you with arrows.
 * All these are defeated by two weapons. Which are merely any two daggers. You have to be able to custom-enchant but that's pretty easy. Here are the two ultimate oblivion weapons
 * The Healthdrainer: drain health 100 for 2-3 seconds (doesn't really matter). Weakness to magic 100 for 6 seconds. Soul Trap.
 * The Sleepgiver: drain fatigue 100 for 2-3 seconds (as above). Weakness to magic 100 for 6 seconds. Soul Trap.
 * The Healthdrainer (dagger) hits about twice a second (daggers are the fastest melee weapon). So the first hit, they lose 100 health. The next (due to weakness to magic) 200, the next: 400, then 800, then 1600, then 3200 (then, if you want 6400, then if you are sadistic 12800). Then the soul can be used, with Azura's star, to recharge the weapon. And now you can kill Mehrunes Dagon (only 10000 health). That's not supposed to be possible.
 * The Sleepgiver (dagger) is the same as the Healthdrainer, but deals the damage to the fatigue of the target. Resulting in the target being knocked out as long as you want to attack. Allowing you to "kill" quest characters about to betray you easily: stun 'em, steal from them (unconscious=instant pickpocket success), then 'talk' to them. They'll betray you in dialogue. Then you slash them to pieces using the Healthdrainer while they can't get upright.
 * Note that all of those are completely nullified by Resist Magicka and/or Spell Absorption at 100%. No wonder there's no multiplayer; everyone would be completely invincible against player attack, unless they die from trap or lava damage.
 * There's a glitch involving summoned armor and weapons that allows you to keep them forever. Doesn't seem like much. But summoned armor and weapons are completely weightless, and completely enchantable. You could theoretically carry an infinite amount of enchanted sets of armor and weapons with ANY of the above gamebreaker enchant combinations. THE POTENTIAL IS LITERALLY LIMITLESS
 * It also helps that the summoned sword you can create and then keep forever is actually a good bit more powerful than the "real" one. In fact, it has the most powerful base damage of any weapon in the game. It makes a really nice infinity-plus-two sword.
 * The same glitch can also be used to make permanent an spell of "temporary increase of stats". Heck, it's possible to find a spell of "temporary increase of SKILLS". It's possible to jump over the whole of morrowind.
 * The reward for the Sheogorath quest is a staff named Wabbajack. Sheogorath is the Daedric prince of madness, and the Wabbajack is equally weird; it transforms the target into a random creature, which could be anything to the lowly rat to the not-so-lowly ogre. However, at a high-enough level, the staff starts breaking games, due to the Scrappy Mechanic. Just about every creature in existence is designed to level up with the player, but the Wabbajack transforms them into creatures that aren't level-scaled. Even if you hit an ogre with the Wabbajack and it turns into an ogre, if you're at a high level (which is ludicrously easy), the ogre will come out of it far weaker than before. Cue a one-hit kill on a monster "designed" for players ten levels lower.
 * Try carrying Azura's Star and adding a one-second Soul Trap spell to your magic weapon. You will kill and automatically Soul Trap your opponent with the same blow, making it impossible to ever run out of charge.
 * The enemies in Oblivion are scaled in difficulty according to the player's level. You level up by sleeping. If you never sleep you will never level, at the expense of not being able to improve your primary attributes (you still can with items and magic) but you will be able to cast master level magic and attacks on a enemy designed for a level 1 player.
 * Following on from the Healthdrainer and Sleepgiver daggers, custom enchanting has developed a new way to kill, instantly, any character, be they technically immortal or not. And the best thing is, you get the target to do it to themselves! Here are the newest tools for any PC who is tired of NPCs. (yes, the names do matter, as NPCs equip enchanted items in alphabetical order)
 * "Assassin's Clothing": Acquire a weightless item (Black Hoods, Mage's Hoods, Dark Shirts, and Black Wide Pants are all possibilities). Enchant with: Damage Health x pts. Effect: The NPC equips, then slowly dies as their HP drains away x points per second. And they won't attribute it to anything. How to use: Reverse pick-pocket the item onto the target (possible due to the item weighing 0. If not, you can't reverse pick-pocket). Notes: More effective than poison apples, as the NPC doesn't need to eat, and will normally instantly equip it. Also reusable. If you want, change the enchantment to: Fire (or any other element) Damage x pt for pretty colors and elemental themed death.
 * "Anasthesia Garment": Works as above, but you enchant with Damage Fatigue 15 pts (you may need other equipment to be enchanted to get to a total of 15 pts per second). With this, give it to any NPC to put them in a And I Must Scream situation. They collapse and are unable to recover. Ever. (DANGEROUS: CAN BREAK QUESTLINES IF USED ON IMPORTANT IMMORTAL NPCS SUCH AS MARTIN!!!!!). The reason is that the NPC equips the item(s) and their fatigue will drain faster than it regenerates. And then they collapse, but will be unable to get up. And if used on an immortal NPC, you've disable them permanently (and lost your item as you can't kill them, so can't reclaim from body). Note: Incapacitated NPCs can still alert guards.
 * "A Silent Death": As above, but enchant with Silence. All mages instantly lose their ability to do anything that can harm you.
 * Unlock spells. Get your alteration skill to at least expert level. Make a spell that opens very hard locks. You will never, ever need lockpicks again (Save for one of S'Krivva's Thieves Guild quests). Combine this with the 100% chameleon suit, add equipment, spells, and potions that do feather, and you can rob a whole city blind. If you use this to steal stuff for the Thieves Guild, the world is your oyster and you can access missions right away by selling all your stolen goods to just one fence.
 * The Atronach birthsign gives you the highest magicka bonus of all birthsigns plus 50% spell absorption at the expense of not being able to regenerate your magicka reserves. Combine this with playing an Altmer (Highest starting magicka out of all the playable races). Stack more spell absorption via enchanted items (The Amulet of Absorption, Magebane Greaves, Greaves of Purity, Sorcerer's Ring, and Mankar Camoran's robe (Provided you get it at level 20) are all good items for this, or wait until you're level 17 to close Oblivion gates and keep save-scumming until you get sigil stones that have 15% spell absorption and enchant other items with them; if you don't want to keep closing gates to get copies of such sigil stones honestly, you can always just get one and clone it with the Skull of Corruption or scrolls) and you will completely offset your Stunted Magicka birthsign effect. Enemies will be unable to kill you as spells and magic weapons will only refill your magicka (High Elves have a weakness against fire, frost, and shock, which is easily remedied with 100% Spell Absorption), so all the game can do is hit you with normal weapons. And if that was not enough, due to an oversight, Spell Absorption works on your own Telekinesis spells. Now the amount of Magicka absorbed is equal to the cost of the spell at skill level 33. This means that if your Mysticism level is above that, you actually absorb more Magicka than is costs you to cast the spell, by the time you master Mysticism, this is five times the amount of Magicka. This makes your Stunted Magicka completely meaningless, as you can replenish your Magicka in a few seconds. Minmaxers Delight indeed.
 * And then there's a trick called "Burning" or "Ripping" using the duplication glitch twice, wearing 1 or an equitable item with a Stat boost will force the item off of you, without taking the boost, noticed this when I was duping Spell Drinkers amulet's, and seeing as you can make Stat Boosting items yourself...

Skyrim

 * Within hours of Skyrim's release, players found that putting a basket over the heads of everyone in a given room allows them to steal everything with impunity. The developers have said they'll leave in any bugs that don't outright break to game or make it unfun. Time will tell if this counts.
 * It appears that they tried to avoid the exponential curve of improving potions from Morrowind in Skyrim, because You can't make Fortify Enchanting enchants, and you cant make fortify Alchemy potions. But you CAN make Fortify Enchanting potions and Fortify Alchemy enchantments. With enough patience and materials, You can keep pingponging the effects back and forth between them, which ultimately can get you potions with such effects as "Weapons and Armour can be improved 3000% better for 30 seconds". This means you can sharpen swords to such a microscopic razor edge that their damage output can be in the thousands per swing.
 * The developers did see this as a potential, and thus even with max enchanting and alchemy skills, as well as all the perks, you can only ever get a modest improvement over both, even if you try to pingpong the effect, as it hits a cap. However, if you drink a Restoration Potion (which marginally boosts both skills), this cap is broken and the pingponging can begin. Because of the ludicrous amounts this can reach, it can literally break the game due to how high the numbers go, and after a certain point (it will never stop) the game simply cannot comprehend the numbers and would just crash.
 * Enchantments on armor can reduce the cost of spells of a given school. These enchants stack additively, and several of them (or just one using the pingponging trick above) can be combined to exceed 100%, making any spell of a given school free.
 * Enchanting is, in general, broken as hell, especially when you start busting out the perks. Two in particular make for some very interesting results - Soul Siphon actually recharges your weapon's power a little when you kill an enemy, so if you have a weapon that has hundreds of charges (Which at level 100 Enchanting, is a 30 damage fire enchant, which is pretty damn powerful) - Running out of charge is practically impossible. However, on the other end of the spectrum, you have Extra Enchant - which allows you to put two enchantments on a single weapon. This can branch off in two ways - You can make a sword which does hideous amounts in the form of a 30 Fire Damage and Frost Damage for example, but this eats through it's power pretty quickly. However, you can also enchant a different sword with elemental damage and soul trap, which gives you a steady supply of soul power to feed your more powerful weapon. And of course, this is assuming you HAVEN'T used the pingpong trick to make these enchants even more beastly.
 * Even better, Enchanting can make it easier to use abilities you had neglected for much of the game: you can drop your casting cost for any one (or two, with 100 enchantment) to zero, make your sneak skill much more effective (with muffle enchantments, you make zero noise, even in heavy armor, and sneak boosts make you harder to see), you can boost the damage for a weapon type (neglected your archery? You can make your bow attacks +100% stronger, or any other weapon). You can make lockpick much simpler. Boost your armor to +100% effectiveness. The only stat enchanting can't raise to gamebreaking levels is hand to hand and, well, enchantment, but it already does that by existing. Which is a good thing, because if you want to reach the level cap of 80-81, you'll need to raise every skill to 100, which gets more difficult the further you go.
 * While enchantment can't raise your hand-to-hand skill, it can affect it indirectly. If you enchant an item to have ludicrous amounts of Fortify Smithing using one of the methods described on this page, you can improve your weapon at a grindstone so much to get one-hit kills on bosses and giants. You can improve your bow to shoot a dragon dead out of the sky as well.
 * Smithing and enchanting: buy a bunch of leather, leather strips, and petty soul gems, make hide bracers until your supply runs out, enchant the bracers with fortify two handed, sell. With high enough speech, you make back nearly all you spent, and your levels in enchanting and smithing go up. It can be also done with forging iron daggers and absorb health enchantments. With enough starting gold, you can max out your enchanting and smithing (you get the same exp that you do making cheap iron and hide as you do daedric gear, and it's about six items per level for both skills). This is a great way to get great gear faster than normal.
 * If you focus on mastering enchanting and smithing first before you work on your armor and weapon skills, you can enchant your armor to boost both your armor skill and your weapon skill to the point the effectiveness of both is essentially tripled. Case in point: with just the perks a character gets as he levels up his two handed skill, a player can have a Daedric Warhammer that does about 100+ damage per hit. Meanwhile, with enchantments that boost his attack damage on every piece of armor that can hold on, the damage is, at max enchanting skill, 300+. This can one hit kill anything short of a lvl 50 dragon or a dungeon boss (on regular difficulty). And it's possible to attain this much power by level 30, meaning that you are essentially unstoppable. The same holds true for your armor.
 * The Endless Stagger: a perk for destruction magic will cause an enemy to stagger when hit by a double cast spell (casting the same spell with both hands so that instead of two spells, it makes a single, more powerful spell). Here's what makes it a gamebreaker: It staggers everything short of an elder dragon, and anything over the novice "spray" spells will stagger any enemy, and if your mana regen is high enough, by the time the enemy is coming out of his stagger (it lasts three seconds, except with dragons, and that just stops what they were doing, be it breath attack, bite, or tail slap, even while airborne), you've gained back the mana you used casting the spell if you have sufficient regen boost and cost reduction.. As long as you cast the spell as your opponent has just come out of the stagger, it will stagger him again. This even works on dragon priests, so you can keep them from getting off any spells if you are quick enough. Use the 0% destruction magic trick above, and you can do this endlessly until the target dies. With Fireball, you can do this to MOBS.
 * Please note, this strategy works best on magic users and archers, as warriors tend to advance rather quickly, and still move forward a little while staggering. Just cast while retreating, and you'll stay unharmed.
 * On another note: Fire magic. Only a small handful of enemies have fire resistance (fire dragons, flame atronchs, dark elves, dwarven inventions to a lesser extent), and many enemies are vulnerable to fire (Spriggans, frost atronachs, all undead, ice dragons), this is the magic to use 9 times out of ten, so it's the best one to put in your damage boosting perks into, and the best one for your weapon enchantments. Lightning comes a close second, since even fewer creatures have lightning resistance, and it drains a casters mana. A sword with both fire and lightning enchantments tacked on is devastatingly lethal fully perked out.
 * Meanwhile, frost just isn't worth the effort: Nords are resistant (and very common), dwarven machines are resistant, most enemy mades are resistant, and the undead are resistant, and the undead are, by far, the most numerous enemy you will encounter in Skyrim dungeons.
 * And now, Skyrim is as broken as Morrowind, with the discovery that all "Fortify X" effects, no matter where it comes from(gear, potion, etc), are considered Restoration-based magic, and are boosted by Fortify Restoration effects. Taking advantage of this lets you make potions that fortify your skills by the thousands and millions in less than ten minutes. Note that, while that video has maxed out Alchemy, doing so is not necessary to take advantage of this.
 * It will, in fact, max out your alchemy within minutes as potions with hundreds of thousands of percent in increase will yield dozens of alchemy skill levels at once. You do require to have at least one Fortify Alchemy bonus to fortify in order to take advantage of this, though it's not too hard to loot or buy one to disenchant and learn the Fortify Alchemy formula.
 * The Oghma Infinium glitch. This book meant to be single-use can be tricked into replicating endlessly, providing full skill and level cap within minutes.
 * For those in the thief's side of things, you can get 30 times damage multiplication on daggers while sneaking and with a certain perk and pair of gloves that only requires a very easy quest to get. With proper mountain-climbing, you can one-shot even dragons. Stealth in general is broken because the Too Dumb to Live AI will simply give up on searching for you no matter how many times you damage them. You can shoot an arrow into a guard's face and walk away and within twenty seconds he will say "must have just been my imagination", even if his partner is lying dead on the floor from arrows to the face.
 * For minimal effort you can make vegetable soup. Eating that gives you a very small amount of health and stamina per second for 720 seconds. This allows you to continually bash opponents. It takes time, but anything you can get 1v1 with can be bashed to death. You take no damage because the bashes interrupt everything they do. There is a perk that increases bash damage in the blocking tree.
 * Plus, a shield that you can get during the main quest, causes additional bleeding damage while bashing, meaning that you can violently impale your enemy on the shield spikes over and over until he dies.
 * Somewhat hindered by the fact that eating several vegetable soups will crash your game if you open your magic menu.
 * Unequipping & equipping gear that increases stamina, health and or mana gives you that amount. The gear change can be hotkeyed. You can cycle identical sets of gear as to continally replenish the stats without ever being without armor. This essentially makes the above gamebreaker to get zero mana cost unnecessary, along with health and stamina potions.
 * Enemy pathfinding is so poor that an archer can just sit somewhere out of reach and shoot everything dead.
 * Elemental Fury (a dragon shout that boosts attack speed with melee) + the Steed stone (a stone whose ability makes armor, even heavy armor, weightless, and as a result boosts attack speed even with two handed weapons regardless of armor) + a perk that boosts attack speed when dual wielding one handed weapons = everything dies screaming. For a two handed weapons expert, Elemental fury and the Stallion stone allows the player in heavy armor to wield a two handed warhammer with the speed of a one handed weapon.
 * The only drawback to Elemental Fury is that it can't be used while carrying enchanted weaponry.
 * Being an Orc is, in many ways, a serious Game Breaker for melee characters. How? Let us count the ways.
 * First, an orc has one racial ability, but it is so game breaking that the developers did not need to give the orcs any other abilities: Berserk. Take half damage, deal double damage, for 60 seconds. You can kill a LOT of enemies in 60 seconds, or one really powerful enemy. As long as you are quick enough, once a dragon lands, an orc can deal 50% of a dragon's health before it can take off, which will cause the dragon to be grounded. From there, you can finish it off without worrying about it taking off and attacking from the air.
 * Second, the freedom to immediately enter orc strongholds. Gloombound mine is the has a the largest number of ebony veins anywhere, and ebony is the material needed to make two of the strongest armors in the game, and you have to enter the orc stronghold that guards it before you can enter. An orc can walk right in with a pickaxe and mine every ore vein in the place, resulting in 10-15 ingots worth each trip. And the mines regularly regenerate their stock. Even before you reach 80 smithing, allowing you to make armor and weapons with it, the ingots do sell quite well. Once you reach 80 smithing, you can easily make Ebony armor and weapons for your own use or for selling. It's free money.
 * Three, the innate bonuses to smithing and enchanting. Using the Warrior stone to boost your experience growth, and orc has a faster and easier time maxing out his enchanting and smithing skills than any other race.
 * Putting these three advantages together, an orc can reach lvl 80 smithing very quickly, make ebony armor for himself very quickly, and use enchanting and smithing to make them very powerful very quickly. Normally, you'd have to be lvl 30 before you could even get ebony equipment in shops. With a training regimen focused on smithing, you can get Ebony gear before you are lvl 20, and it will only improve from there.
 * Conjuring Dremora Lords. Get at least 65 Conjuration and you can summon one of these guys. They're strong enough to go toe to toe with most things and win. Dragons included. Even of they're killed, you can simply summon another one. Then another one. Then another one. Repeat until your target(s) are dead. This becomes even more effective once you get the perk that halves the cost of casting it. Then, you can make it even more effective by getting the Twin Souls perk, which allows you to have two summons at a time. Two Dremora Lords against anything is pretty much a Curb Stomp Battle.
 * For those not understanding why this is such a powerful gamebreaker (maybe you fought Dremora Lords before and were not impressed), a dremora lord is summoned with a powerful two handed daedric greatsword that is always enchanted with additional fire damage, and wear daedric armor. Unless you're playing on harder difficulties, most enemies will never wear anything above steel plate (and those are typically bosses) so your opponents are almost always out-classed.
 * The Mannequins in Honeyside can be exploited to duplicate any armor in the game. While any mannequin can do this, Honeyside is the easiest to obtain. This can allow you to duplicate expensive armors to sell, or duplicate armors that are only attainable once, such as the Nightingale Armor (coincidentally, the quest you need to start to get the Nightingale armor is the same town Honeyside's in: Riften).
 * Certain skills can be freely and cheaply maxed out without using them whatsoever. The earliest example of this is the Faendal exploit, where you can pay him to train you, then take back the money due to him being a follower. The companions hold 5 members who can do the same thing, but they're better in that they're not capped at 50 per skill like Faendal is (two of them are capped at 90, the highest trainers can go). The catch is you have to complete the Companions questline before you can take back the money. In addition, casting Soultrap on cows does not kill them, but levels your Conjuration. If you can find an isolated cow and a way to regen your magicka, you can reach 100 in Conjuration almost instantly.
 * Surprising Oblivion players, Archery can very easily be this. Get a bow, enchant it with Paralyse for 1-5 sec and the unique Firey Soul Trap enchantment (10 pts fire damage, soul trap between 1-10 seconds) and a grand soul. Set soul trap and paralyse to 1, and you have a bow with several hundred charges that almost completely refills even from a petty soul and deals bow damage +10 fire and has a 50% chance to make anyone it hits fall down (the falling down and getting up animation makes the 1 seconds Paralyse actually last for closer to four seconds). Put this on, say, a crafted daedric bow and sneak attack and you're doing enough damage to one-shot ANY humanoid, or two-shot a mammoth.
 * A simple, rare alteration spell, Transmute, can easily be this. It's almost impossible to find in shops, but it can be found in Halted Stream Camp, a bandit lair in walking distance of Whiterun, on a table in plain view. The spell does two things: when cast, it will turn a single piece of iron ore into silver, or a piece of silver ore into gold. Let me repeat that: two castings of the spell will turn a lump of iron ore, the most commonly found ore in the game, that has multiple mines spread through Skyrim, into one of the most expensive. An adept level spell, it has a high mana cost (nearly 100), but with high mana regen, you can spam it repeatedly, and an adept in alteration can cast it at lower cost. Turn the gold ore into ingots, then jewelry, enchant them, and you have some high grade vendor trash to sell. This allows you to raise both smithing, and enchanting, easily (enchanted rings and necklaces sell quite well). It's practically money for nothing. The best part? Halted Stream Camp, the best place to find it, is AN IRON MINE. You can dig at least 15 iron ore after you clear it, and you won't even need to bring your own pickaxe, the can be found all over. Just one more reason to play a mage.
 * The most basic conjuration necromancy spell, Raise Zombie, can easily be used to raise your conjuration to level 50 by the end of Bleak Fall Barrow. How? Cast it on a corpse, then strike the raised creature with the weapon and/or attack spell of your choice, until the creature goes hostile. The moment it does so, you get a large amount of experience in conjuration. Why? You only get conjuration exp if your raised zombie engages in combat against something. That something can be anything, even yourself. As long as you don't kill the zombie before it turns hostile, you'll raise both your conjuration and your attack skill. And zombie raising gives a TREMENDOUS amount of exp compared to daedra summons. Just cast it on any basic enemy (bandit, drauger, skeever), make it turn against you, kill it, and you'll be leveling up lightning fast. The best part? Any corpse will do, even ones that were dead before you entered the level. Bleak Falls Barrow is littered with basic corpses that you can raise then rekill to boost you conjuration at lightning speed. Oh, and if you've mastered illusion, you can just raise the creature, cast fury on it (only possible with the perk that allows illusion spells to affect the undead), and you'll get the exp automatically. Even if you only intend to use bound weapons, this trick will let you have the levels necessary to get the Bound Bow spell (most expensive, requires level 50 conjuration) and all the perks relating to bound weapons by the time you clear the barrow. Plus, there's the fun of getting to kill your enemies a second time.
 * To guarantee raising your conjuration raises to 50 before the end of Bleak Falls Barrow, be sure you get Bound Blade, then cast it before you aggro your zombies. This will cause your level to raise at double speed, since having a bound weapon out when combat starts will raise the level. Just be sure you use weak attacks to aggro the zombie before finishing it off. If the zombie dies before it can aggro (Skeevers are prone to this), you get nothing. Best use an iron dagger, or for a non-Khajit, bare hands.
 * Smithing and Enchanting combined can be a tremendous gamebreaker: First, max both out. Next, create a set of gear that boosts your smithing. Craft a set of daedric armor and your weapon of choice. Use your smith boosting equipment to improve them to ridiculously high levels. Now, enchant your gear so that it boosts your weapon skill and health regen astronomically, plus fortifying health where possible. Place whatever weapon enchants you please on your weapon, but fire, frost, and shock aren't advised (you'll see why in a second). With a set boosted with both smithing and enchantment, your damage output is in the hundreds regardless of your weapon. A Daedric warhammer, at max two-handed skill, with this setup will do 300+ base damage per swing, while the basic weapon enchants would only allow an increase of 30+ additional damage (60+ if both enchants deal damage). You may as well keep your weapon unenchanted so you can use elemental fury to maximize your attack speed. With the health regen enchants and your maxed out damage reduction from the armor, you're nearly immortal unless your ambushed by multiple draugar deathlords armed with ebony and you just stand around like a loser while they pound on you. With maxed regen enchants, most basic enemies literally cannot kill you no matter how hard they try: your armor negates their damage to pathetic levels, and the regen restore your health completely before their next attack. With this build, you don't even need any of the other breakers listed above, this one is enough to let you go toe to toe anything out there with ease, without having to use any exploits, glitches, or cheats. Just 100+ smithing and enchantment combined with the right enchants will make you a near-god.
 * The Conjuration Spell Bound Bow can be a tremendous Game Breaker with the right build. Why? Well, in addition to the other reasons a Bound weapon can be a gamebreaker, or at least a Disc One Nuke, they come with one special feature: Regenerating Daedric arrows. For those who are unaware, Daedric arrows are super-rare, and very expensive, to the point you'd save them for bosses, and even then, only for very tough ones. Bound Bow comes with 100 Daedric strength arrows each time it is cast, meaning you don't have to worry about wasting expensive arrows. Plus, it's boosted by Archery Perks and fortify archery enchants, allowing you to raise the damage further. Combine it with Sneak, and the x3 sneak damage enchant, and with a regular attack, it can do up to 150+ damage per shot, 450+ damage per sneak attack. To maximize it's sneaking potential, the Illusion 50 perk for silent spell casting is very important, but if you spam the spell Muffle (one of only a small handful of spells you can spam that will raise exp and grants a huge exp amount when cast), you'll have that in no time.
 * A spell that you can find in the Mage Guild Quest in Labyrinthian, Telekinesis, can quickly raise your Alteration to 100 in minutes. While granting high exp when cast, it's high mana cost usually prevents it from being usable. With enchantment, this is easily overcome. Craft an equipment set to minimize Alteration spell costs to as close to zero as possible, then cast telekinesis on an object, preferably one in your house. Just hold the object, and your levels will raise lighting fast. You can reach 100 in less than twenty minutes. Just hold the button down.