The Dev Team Thinks of Everything/Fallout

"Raul: Right. Got it. I'll just stop using this melee weapon and instead use a melee weapon. Good idea, Boss."
 * Fallout 2 has a healing device called a Super Stimpack, which heals massive damage instantly, but has a timer that inflicts some less-serious damage later on from harsh drug side-effects. It is possible to assassinate the Enclave's president by healing him with about ten of them. There is a special text message for this eventuality.
 * Along the same line, you can use the drug Jet on the enemies to cripple them before a fight. Jet is a very powerful combat enhancer, but after about 10 minutes of game time, gives you very big penalties. You can use 3 Jet in the Enclave base on every soldier, wait about 30 minutes, and every soldier will be effectively blind and cannot hit you at point blank range.
 * In Fallout 3, using the pickpocket command to deposit a grenade or a mine in another person's inventory will a) automatically activate it and b) give you an achievement for doing so.
 * The last level in Fallout 2 is supposed to be a running shootout through the Big Bad's home base. However, if you have the same kind of Powered Armor the Bads use, you can drop off your allies at the front door and bluff your way through the entire mission, save the battle at the end. Which you can allow temporary allies and base guns to deal with instead of handling it yourself.
 * Early on in Fallout 3, you are given the opportunity to do a fairly long sidequest that is essentially an optional, extended tutorial, one stage of which involves investigating an old robotics factory. Another sidequest, normally started much later, involves two "superheroes," the AntAgonizer and the Mechanist. There is special dialogue for accepting the sub-quest to go to the robotics factory while wearing the Mechanist's costume.
 * Remembering that the Antagonist is based on a comic book character, it's possible to use info found in the publisher's ruins to make her give up her life of villainy.
 * If you talk to Stockholm (a sniper in Megaton who is normally unreachable) by using the command console to make yourself fly (or give yourself godmode and launch yourself upward with a mini-nuke and land just right), he will chat like other NPC's, and end the conversation with "And how the hell did you get up here, anyway?"
 * There are actually two Stockholms: one for the Megaton city cell itself, and one for the overworld outside Megaton. They are actually two separate entities (albeit with identical appearance and dialogue). Killing one will automatically make the other disappear.
 * One of the DLC packs for the game requires you to talk to a few Brotherhood of Steel renegades called the Outcasts. After helping them with a Super Mutant problem, you almost immediately engage in conversation with them. If you happen to be wearing armor that you took from the dead body of an Outcast elsewhere in the game while they talk to you, they start asking what the hell you're doing off-duty.
 * If you kill Lucas Simms, the town Megaton's sheriff, his son will have new dialog options with you. Moreover, if you start wearing the Sheriff's outfit, his son will say "You might wear this badge,but you're not my dad." Other NPCs will react too!
 * The Power of Atom, in which you either disarm or detonate the nuke in Megaton, is likely one of the first quests you'll get in the Wasteland, and is usually done right away as it results in the only available player housing in the game. Holy Water is a quest that is only available near the end of the game after the main quest is complete and you've begun Broken Steel content, and it starts just outside of Megaton. If you somehow happen to blow up Megaton while Holy Water is active, there is a set reaction from every NPC involved.
 * In Fallout New Vegas, in a mission given to you by The King, you have to investigate a bodyguard named Orris, that seems to be doing his job a little too well, he does this through paying thugs to play dead while he fires blanks, giving the illusion of skill, but if you decide to go back and attack the thugs on the ground, they get up and yell, "Oriris 'aint payin' us enough for this!", and attempt to kill you.
 * Faction leaders Mr. House and Caesar tend to congratulate (or scold if the player did something to annoy or anger them) the player on things they have done. Mr. House, for instance, will praise the player if he immediately goes and retrieves the Platinum Chip instead of talking to him, while Caesar will offer praise if the player kills Mr. House as soon as he enters the Lucky 38.
 * Almost all of Mr. House's dialogue has a corresponding line from Yes Man. If you kill House and install Yes Man into the mainframe before going after the Platinum Chip, it will be Yes Man that greets you inside the Securitron Vault. He will also give the demonstration on what the Mark II upgrade does in House's stead.
 * Alternatively, if you pursue the independent ending without upgrading the Securitron army, he will scold the player (as best he can anyway, given his programming) for trying to take on Caesar's Legion and the NCR without a standing army.
 * Whenever you have a companion, try to give them an order you already gave them a few seconds ago and see the results.


 * Dropping the (hard-to-find) radiation barrels on Cottonwood Cove will result in the Legion ferryman donning a radiation suit on subsequent visits.
 * Bypass Nipton on the way to New Vegas, thereby avoiding meeting Vulpes Inculta. Once you get to Vegas and meet Vulpes Inculta, kill him, then go all the way back to Nipton. A unique, named Legionaire will be in command at Nipton instead of Vulpes that you can talk to instead.
 * If you do the same thing, minus killing Vulpes, he will acknowledge that you've met, though he "Wasn't wearing a dog's head at the time."
 * In Dead Money, you can find 12 skill books, one for each skill except Survival. Survival's book? Fallout 3's The Wasteland Survival Guide.
 * At the end of Lonesome Road, the player has an option to  One-Scene Wonder NCR President Kimball never goes to make his speech at Hoover Dam at the end of the game. Why?.
 * When you load a game in a casino in Fallout: New Vegas, dealers swap decks, croupier check the wheels against bias and slot machines are resetting themselves for one minute as an anti-cheating measure.
 * In Old World Blues, a required quest involves you entering a chamber containing Gabe, the cybernetic dog of Doctor Borous while he was still human. Gabe is hostile and immediately attacks you. You'll almost certainly be forced to kill him, but you're not required to, and even if you dig up the item you need from one of a dozen dirt piles around the chamber, roboscorpions will attack and almost certainly kill Gabe if you didn't. But if you did avoid killing Gabe and protected him from the roboscorpions (neither of which the game even really hints is possible), Doctor Borous has unique lines thanking you for sparing his dog when you bring Gabe's bowl back to him.