Plot Lock

Sometimes video games have to stop you from getting where you want to go. We all know the routine.

But picture this. You're playing a thief character, and you encounter a locked door. Your thief can pick the locks on palace vaults with ease, so why is this wooden door impervious to your attempts?

You've been stopped by the Plot Lock. A Plot Lock is any example of a Broken Bridge where, for whatever reason, the character should be able to overcome it, and yet they can't in this one arbitrary situation (where doing so would, of course, break The One True Sequence). On the other hand, not using Plot Locks can sometimes lead to massive Sequence Breaking, which occasionally is even more of a Wall Banger than the Plot Lock itself.

Note that it's only a Plot Lock if you're supposed to eventually get the key to the door. If it's just locked because there's nothing behind it, it might have been Dummied Out, but it's not a Plot Lock. It's also not a Plot Lock if there's no reason your character should be able to get around it - then it's just an ordinary Broken Bridge.

A funny subset of these is when it specifically states that a key is required. So all those other doors we opened before didn't require a key?

Compare Insurmountable Waist High Fence, Cutscene Incompetence, and Plotline Death. Also compare Statistically Speaking, where your character can never get past a particular kind of obstacle even if his statistics indicate he should be able to.

"Frohman: [...] He's using my Gravity Gun to punt a car out of our way. But a wooden door, well. Let's just run eight miles through soldier-infested, mine-littered streets to avoid it."
 * Okami does this a couple of times:
 * You can't fix the Broken Bridge between Agata Forest and Taka Pass, even though Ammy can paint them good as new everywhere else.
 * When you enter Orochi's castle, there's a broken staircase. Rejuvenation won't fix it. You're forced to jump down into the chasm and work your way through the level.
 * Oblivion has locks that can't be picked. Morrowind averted it: An Open spell with a strength of 100 (which is the maximum lock strength) could open any door, as could a master lockpick.
 * Daggerfall also suffered from this, although you could expect as much from a game that allows you to scale almost any vertical surface. Some walls can't be climbed, arbitrarily. Also, your freedom of movement is crippled by the inability to climb down.
 * The later Halo games don't have fall damage, but they do have arbitrary drops that kill you to prevent you from jumping down to where you need to go.
 * Doctor Who has the deadlock seal, which the sonic screwdriver can't unlock, appearing on various locks from all places and times for no apparent reason.
 * In less technologically advanced settings, wooden doors thwart the sonic screwdriver just as easily.
 * The Grand Theft Auto series does this. If you start from the beginning, but you've played it before, you'll notice all the places that are impossible to get into that are possible later on. There's no lock to pick or anything, it's just that the character refuses to turn the knob to the door and walk inside. After you complete a task, there will be a glowing area in front of that building and you can then enter it.
 * Knights of the Old Republic gives us an In-Universe example by having locked doors that can be opened by the PC if s/he has the skills or items needed, and then there are the sealed doors, which can only be opened by finding the right computer.
 * Bonus points because the character is often carrying a lightsaber.
 * In Tales of Symphonia, your characters have all demonstrated the ability to make flying leaps and large jumps, and one or two of them can literally fly, and does so in-game. However, when there's no context-sensitive action to do so, you can't go over the Insurmountable Waist High Fence that you will undoubtedly have to go through a complex series of events to make a little bridge to get there.
 * In Baldur's Gate doors often do not have an ordinary locking mechanism and may be warded against simple spells. You'd think that by the time you're a 40th level unstoppable killing machine with spells to stop time, summon powerful angels and demons, and wreck incredible destruction with a flick of your wrist, you would have learned a complicated spell to open doors, given how many are protected this way.
 * There's a similar problem mechanic in Neverwinter Nights.
 * Especially irritating since many of these doors should be vulnerable to a peasant with a chisel and a hammer.
 * In Splinter Cell, a door that is "locked" can usually be either picked or hacked, depending on the particular locking mechanism in place. If the door is "jammed", however, it won't typically open until some specific plot event.
 * In Mass Effect, three of your characters (and possibly you, depending on your job) are able to defeat electronic locks, and everybody can simply force them open with enough Omnigels. However, some doors are simply unopenable until you get to the mission where it's supposed to open.
 * Mass Effect 2 highlights all player-usable doors with holographic symbols. Unlocked doors have green symbols and hackable doors have orange ones. Plot Locks have red. Every time you see that red symbol, you know you'll be back later, because cosmetic doors that cannot open at all don't have any symbols on them.
 * The Half-Life series has innumerable Locked Doors that require the player find another route to the required destination. This is reasonable for areas where the player is not intended to go, but not so for Space Filling Paths that loop back on themselves and create a Door to Before, when Gordon could simply blow up the flimsy wooden door or, in the second game, just punt the damn thing with the incredibly useful Gravity Gun.
 * Concerned gleefully lampshades this.


 * Nightmare House, among other Source mods, egregiously abuses this trope. It's not uncommon in Nightmare House 2 to find that a door is locked, be given the requisite plot exposition or orders to go through the door, and then find it magically unlocked. This is a common sight that can be seen in many of the LPs online. The player is also given a shotgun late in the game that had been seen blowing open locked doors, but finds it unable to take down anything tougher than an empty wooden crate.
 * Fallout 3 has numerous doors that are marked as "INACCESSIBLE" or "REQUIRES KEY" rather than "Easy", "Medium", "Hard", or "Very Hard". Some don't count, as the player is never expected to go there. Others do, as they are opened by plot events.
 * This (along with many other RPG tropes) is made fun of in Labyrinth of Touhou. On the second floor, you have to find a way to bridge across a gap to a treasure chest, in spite of Marisa's arguing that everyone in the party can fly, so why don't we just do that. (They ignore her.)
 * The Winx Club video game also has a few obstacles (e.g. a boulder on the path) that overlook the fact that all of the titular characters can fly.
 * Bionic Commando forces the player to go where the developers intended by placing lethal clouds of radiation everywhere else. At one point the player is fighting a helicopter on a rooftop and is barred from simply jumping off (the protagonist is immune to falling damage) by this radiation. However, once the helicopter is destroyed, it crashes into the building and our hero narrowly escapes the explosion by... jumping off the roof.
 * Resident Evil loves this trope, as many of the games have a playable character who can pick locks, and yet is usually forced to find keys anyway.
 * Any "locked" door in the Silent Hill series eventually opens one way or another, but if the door is jammed, broken, or "shut tight", it stays shut for good.
 * In the later games of the Geneforge series, some locked doors are simply "too complicated to be picked" irregardless of your Mechanics skill or how many lockpicks you have and can only be passed after finding the key.
 * Metroid: Other M may be the ultimate example. Every Broken Bridge that isn't a locked door is passable by using one of Samus's abilities. Which (except for two) she already has. But she has chosen to only activate her abilities when specifically told to, which happens at arbitrary locations in the game.