A Plot Lock is an in-game barrier that is immune to everything but the strongest force in the universe — the needs of the plot. No matter how ingeniously you apply yourself, how many skills or strength does your character have, nor even the futuristic tech or incredible magic that can be wielded: that door isn't opening until the script says it does.
It is often a form of Railroading, or better a tool to enforce it. To avoid going Off the Rails or Sequence Breaking, certain locations are prevented until it is necessary for you to do in order to continue your mission (if the location is related), or until getting there won't give you tools that could unbalance the normal story (if it is in a side quest). For the same reason, the presence of a Plot Lock can also be an Interface Spoiler: when the game tells you that a door cannot be unlocked no matter what, in a game where you can open previously locked doors, that likely means that you will return in the future with the capability to enter.
It is not mandatory though: sometimes a Plot Lock is only for some special areas you can access after you defeated your strong opponent, with in-universe story details about your journey at this point, but no direct effect to the quest nor items that could change your path.
Compare Kill Enemies to Open, 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.
Examples from video games:
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Action-Adventure
- In The Legend of Zelda: Breath of the Wild, the player can use a whole variety of glitches
to reach Divine Beast Vah Medoh in the sky without recruiting Teba to destroy the mounted cannons. Unfortunately the collision is turned off until you do, even if Link reaches the Divine Beast he will pass right through the walls and floor.
- Ōkami 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. This becomes obvious when you go back in time to when the staircase was still whole, and you can just go up it and confront Orochi directly.
- 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.
Adventure
- Bill Nye the Science Guy: Stop the Rock! has the Nye Labs Sky Labs (the atmospheric research wing of Nye Labs), whose password can only be gotten if you choose the "Join Nye Labs" (Story Mode) in the beginning. If you chose "Hang Out" (Sandbox Mode) instead, not only is it impossible to get the password, all the access doors to the Sky Labs have "Access Must Be Approved by Bill Nye" on their displays, and said approval is also impossible to get.
Driving Games
- 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. Makes sense with safehouses you haven't bought yet, but why in god's name are you not allowed into the hairdressers until someone tells you where it is?
First-Person Shooters
- Most of the Call of Duty games don't allow you to open doors yourself, so you must wait for your teammates to do so. Some obstacles also can't be surmounted until the plot allows you to.
- 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. 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.
- The later mainline Halo games generally 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.
- In Wolfenstein, certain doors in the Hub City of Isenstadt are locked until the player is briefed on specific missions, or beaten all missions in a given area if the door leads to another section of the hub.
Massively Multiplayer Online Role-Playing Games
- Although the Beef Gate is the most common way to keep low-level players out of high-level areas in The Lord of the Rings Online, there are a few doors that are level-locked. Attempting to open them usually results in an ambiguous message, ("your level is too low") but the developers sometimes list specific levels when these doors are first installed. For example, a recent update introduced a door in Bree-town (one of the starting settlements) which restricted access to level 90. As the current level cap is 75, this might (or might not) indicate how high the cap will be raised in the Riders of Rohan expansion.
Platform Games
- 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.
- 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.
Role-Playing Games
- Arcanum: Of Steamworks & Magick Obscura has a handful of containers that are immune to such treatment: The Iron Clan Chest in Tarant has infinite health and an infinite-strength lock, the Iron Clan Vault has a different opening mechanism, the doors in the First Panarii Temple are "magickally sealed" until you reach the right point in the plot, and Qintarra and T'sen-Ang have "magick barriers" in place that require permission from the guards to open.
- In Baldur's Gate II several buildings and areas have doors that can't be unlocked until the plot or a side quest dictates so. You can recognize them because if you try to lockpick them, the game will give the feedback "the mechanism that operates this door does not have a conventional lock and may be warded against simple spells". No matter how much skill does your character have, they're impossible.
- And this becomes even more egregious in Baldur's Gate II: Throne of Bhaal: here you even have sewer manholes that don't have conventional locks and are sealed against simple spells, until you get the appropriate special keys to go down. Truly they must be divine sewers for having such wardings, blessed with the direct presence of the gods themselves. Considering how rushed was the expansion, it is a cheap method to prevent going Off the Rails with limited areas available and scripted encounters. Still, 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.
- In Dragon Age games, doors with these will pop up a "Key required" message when you click on them. This continues happening even if your rogue is the greatest lockpicker to ever live.
- Though several entries in the Dragon Quest series have a Thief class, they're never able to pick any of the locked doors you encounter along the way.
- The Elder Scrolls:
- In Daggerfall, the "Climbing" ability otherwise allows you to scale almost any vertical surface, but some walls arbitrarily cannot be climbed. Further, your freedom of movement is crippled by the inability to climb down.
- In Morrowind, with a high Security skill and a decent quality lockpick, you can unlock any door in the game. In most cases, however, you'll be told to leave the area if you aren't supposed to be there yet (such as when picking the lock to get into Vivec's temple). The Tribunal expansion adds a single door which cannot be unlocked at all (the door to King Helseth's chambers).
- Oblivion adds locks which simply cannot be picked, even if you have a maxed out skill and the Skeleton Key. You must have the key in order to open these (usually quest related) locks.
- Skyrim has quite a few dungeons that are involved in faction quests which are locked until you receive the key for the relevant quest. Snow Veil Sanctum deserves a special mention, since there's no claw to open the Nordic puzzle lock and Mercer Frey unlocks it using the power of the Skeleton Key.
- In the later games of the Geneforge series, some locked doors are simply "too complicated to be picked" regardless of your Mechanics skill or how many lockpicks you have and can only be passed after finding the key.
- Neverwinter Nights has some doors that cannot be opened with all of the character's power, yet are vulnerable to a peasant with a chisel and a hammer as the plot demands.
- In Persona 3, you're tasked with climbing Tartarus as far as you can, and you must reach the top by the end of the game. But to prevent power-levelers and New Game Plus players from blowing through it during the first night, there are arbitrary "barrier floors" every few dozen floors, preventing you from climbing further with an Insurmountable Waist-Height Fence. These barriers tend to go away on their own after plot-driven events, for no reason at all other than some "mysterious force" is removing them.
- Pokémon:
- The game uses NPCs and wild Pokemon to block your path in certain games until a plot point has been resolved. You can teach certain Pokemon the move Fly, which instantly flies you from one town to another (but only towns you've already been to). The Fridge Logic sets in when you can't fly ten feet over that guy's head.
- This is also the reason for the existence of HMs - in the Gen 1, for example, you were required to go to the S.S. Anne to get the HM for cut, which was needed to get to the Vermillion City Gym. However, by this point, the player likely had at least one Pokemon who could've either cut or burned the tree down. Starting in Gen 7, however, this example is averted, since HMs are replaced with Ride Pokemon, and in those cases, all instances that require Ride Pokemon are ones that clearly would not be accessible on foot.
- Similar to HMs, there are certain Key Items that are required to pass by certain obstacles that seem like they should be passable without the item - for example, in Gold and Silver (and their remakes) with what seems like a tree blocking the player off from National Parknote and Route 37note , and players are required to have the Squirt Bottle - while not being able to take it out with Cut is justifiednote , one can't help but feel frustrated if one has chosen the water-type Totodile as their starter.
- 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. Infamously, there's a sequence a few hours in where Colette uses her newly acquired angel wings to fly up to an unreachable platform and get a necessary key... which she will never do again for the 40 hours left in the game, for literally no reason.
- This (along with many other RPG tropes) is made fun of in Touhou Labyrinth. 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.)
- In The Witcher 3: Wild Hunt, "Locked. Key required." is a notification you'll see semi-regularly even on wooden doors in rickety houses, despite the fact that elsewhere Geralt can use the Aard sign to blast down doors, walls, rock piles, and stalagmites.
Survival Horror
- 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. Many of the protagonists are also ex-cops or military, some of whom are wearing combat gear in their stories, yet they cannot even kick down doors explicitly labeled as "rickety."
- 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. Starting with Silent Hill 3, the protagonist will turn their head towards usable doors.
Third-Person Shooters
- Fallout 3 and Fallout: New Vegas have numerous doors that are marked as "INACCESSIBLE" or "REQUIRES KEY" rather than "Easy", "Medium", "Hard", or "Very Hard". The "INACCESSIBLE" ones don't count, as they are, well... inaccessible — you never get to use them. Others do, as they are opened by plot events. Some "Requires Key" doors can only be opened via hacking, and usually lead to empty rooms or a void of nothingness.
- 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.
- 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.
