Inescapable Ambush

"Defeat enemies to unlock doors."

- Metroid Prime (PAL version)

A specific type of enemy encounter common in a variety of video game genres. When the player enters a specific area, some type of barrier is closed around the player character (even one as simple as a door that mysteriously shuts and locks itself), and they cannot leave these narrow confines until all the available enemies are defeated.

This is commonly used as a way to set up a Boss Battle (though not all Boss Battles are Inescapable Ambushes).

In some games, if your characters gain enough experience in a certain trait, such as awareness or agility, they may be able to detect potential ambushes and/or evade them entirely.

A huge cause of Useless Useful Stealth.

Longer or more plot-involved examples may extend into an Involuntary Group Split.


 * In The Legend of Zelda series, these often take the form of a dungeon room that seals itself when Link enters, and unseals when all the enemies are gone.
 * In Twilight Princess, the portal locations are a side effect of Link being ambushed by shadow beasts, who show up in a group and erect a force barrier similar to a boxing ring around themselves. When Link defeats them, the portal becomes available.
 * Also in Twilight Princess, at several points in Hyrule Castle, Link gets sealed inside magic barrier rings and attacked by enemies (that for some reason can walk straight through them).
 * Because their boss wants them to and doesn't want Link to, of course.
 * Though in many of the earlier games, it was possible to remain in the doorway of the ambush room and check out the situation, allowing you a quick retreat if necessary.
 * In all the Pokémon RPGs, when the main character enters the Elite Four's rooms, he cannot go outside until he defeats or is defeated by the Elite Four and the Champion.
 * Done most cleverly in the Gen IV games (D/P/Pl), where a platform takes you from each trainer to the next, and returns to its original position after you step off.
 * In Seiken Densetsu 3, there are certain rooms in dungeons that will trap the player until all of the enemies are defeated. Of course, every single boss battle is like this as well.
 * Fable had the nasty habit of erecting forcefields around the room you are in whenever you fight certain monsters or during ambushes.
 * Soul Reaver 2 had similar forcefields generated by certain types of time demons when you faced them. You didn't have to kill all the monsters, just the one casting the barrier.
 * Devil May Cry has barriers that flare into life when you walk into certain rooms, whereupon the enemies usually arrive via Cutscene. Interestingly, if you get too close to a barrier, it briefly forms into a hand and takes a swipe at you.
 * In the Kingdom Hearts games, not only do these lock Sora in, but they often lock Goofy and Donald Duck out, forcing you to battle one-on-one with the boss.
 * In a humorous aversion of Gameplay and Story Segregation, Goofy slams right into one of the invisible walls, and Donald is knocked out of the area by the boss, leaving Sora to fight him alone.
 * Some boss fights in 358/2 Days avert this trope by creating no barriers after you enter the area where the boss resides. This is oftentimes more annoying than if the game had prevented you from exiting, as it is painfully easy to accidentally exit and when you re-enter, the boss is at full HP again.
 * God of War essentially swiped the barriers from Devil May Cry; the only difference is that the barriers in this game turn into a fate's head instead of a hand.
 * Nearly every single room in Castlevania: Lament of Innocence acts this way the first time you visit it.
 * And on "Crazy" difficulty this happens every time you enter a room.
 * The other 3D Castlevania, Curse of Darkness, tones this down considerably. There's actually a separate theme for the inescapable ambushes: "Followers of Darkness - The First".
 * Of course, the Metroid series, which erected grey barriers in front of the doors during any major boss battle.
 * An interesting variation happens early in Super Metroid where one obtains the bomb ability. In this case, the door locks after obtaining it, contrary to all other such rooms. This has provided a way for tool-assisted speedrunners to skip the fight, though just barely.
 * Super Metroid has an interesting variation, in that the door to Tourian only opens when you defeat the main bosses. One wonders why they would set up the door to their main computer system only when those charged with the defending it are dead: the exact opposite would be more secure.
 * Exception: Chrono Cross, where every battle could be escaped, including the final boss. It should be noted, however, that running from most bosses gives you no real advantage: you will immediately be drawn back into battle again, with no chance to say, rearrange elements. Still, infinite retries is useful enough...
 * Near the end of the first level in the first mission of Medal of Honor: Allied Assault, the ambush in question loops endlessly until you accomplish your given objectives. You could waste your ammo on German soldiers, hide near the locked exit door, etc. until you pick up that machinegun and shoot!
 * At the end of the second mission, after blowing your cover, you have to push your way through several respawning ambushes.
 * Sonic Rush Series has several of these in three of its zones.
 * Okami conjures up a barrier decorated with kanji around every battle. In all but a few of these fights, you can run from battle by breaking through the barrier in a certain spot.
 * Justified in Phantasy Star Online, which explains that this is a security feature that locks the doors when wild creatures are nearby.
 * Although generally it left the doors already opened unlocked allowing you to escape, some cases however did lock you in a room leaving you only with the ability to warp out to heal and then come back full equipped (not true boss fights).
 * Happens in Half-Life 2, Episode 2, during the "White Forest Inn Siege". While the player and sidekick are driving down a seemingly deserted street, force-fields activate at either end of the road and Combine soldiers pour out of the woodwork. The player is forced to retreat into a hotel in which, for some reason, all the exits are locked except for those inside the force-fields.
 * Partially subverted at the end of the siege, as the force-fields don't magically disappear when the last enemy dies. Instead, the final wave of enemies break down the previously locked doors while storming the hotel.
 * The Elder Scrolls IV: Oblivion includes several ambushes with inexplicably locking doors. Two optional side quests end in rooms (for example, a farmhouse and a family tomb) where the door suddenly locks behind you, with no suggestion of minions waiting outside to trap you. This is actually inconsistent with most of the gameplay, because as fantastic as Oblivion may be, the storylines usually adhere to common sense.
 * Lock spell?
 * The lock spell was Dummied Out of Oblivion; no spell or scroll left in the game provides the effect. You can only acquire it through the console (~) in the PC version, so if magical locks are indeed what's going on, then The Computer Is a Cheating Bastard.
 * I am not sure about the reference to the farmhouse, but the family tomb example is justified: the Big Bad of that particular sidequest is one of the two that ambushes you, and he carries the key you need to get out. The implication is (naturally) that he closed and locked you in with himself and his ally after they entered behind you (granted, they entered almost instantaneously, but...).
 * All boss fights in Drakengard take this form due to Gameplay and Story Segregation: one would think being on a dragon would let one just fly away if they wanted to. Also happens and played straight when in the Forest, as the Fog of War tends to obscure enemy positions until it is too late.
 * Averted in the MMORPG City of Heroes, where you can easily outrun your would-be ambushers. Of course, this can lead to high-level ambush groups wandering around a low-level zone, with predictable results.
 * Some high-level players do this on purpose, for laughs.
 * Also played straight with ambushes that know exactly where you are. Even if you're stealthed. Even if you're a Stalker and the enemies who ambush can't normally see you.
 * Multiple Kirby adventure games have these. There is a common ambush song across the series (sometimes remixed).
 * Prince of Persia: Warrior Within has a annoying version. There are rooms that can only be escaped with the prince's Le Parkour skills, which can't be used with your sword drawn. The Prince will not sheath his sword until all the enemies are defeated.
 * Made even more annoying by the fact that Prince draws his sword even when enemies are below you and you can simply jump over a few times, thus completely ignoring the encounter. So Prince forces you to go down and kill everybody.
 * No More Heroes does this during most boss fights, and in some Mook Fights as well. The most annoying one being, that shrinks the arena during the fight twice. As your opponent is , this makes the fight a frustrating experience to say the least.
 * Final Fantasy X 's Mimics shut off your Escape and Flee commands if you steal from them while they're in chest form (thereby exposing their true forms).
 * Which is why you always Mug chests. Although in most areas with Mimics, there are no real chests in battle.
 * At one point in Chrono Trigger, you can talk to some random mook that tells you to be quiet without looking at you because... he's planning to ambush a group of adventurers and doesn't want to be overheard.
 * Welcome to Wario World! There's an enemy in this game that only shows up on your first playthrough. There's an inescapable barrier around him for a small part of the level, and Wario will only be able to continue when he's smashed his puny crystal in.
 * Super Smash Bros: Both the Adventure Mode in Melee and the Subspace Emissary in Brawl often have these. Neither game bothers with barriers (after all, that wouldn't work with the "getting knocked out of bounds'' element) but simply won't allow you to move any further in the level until all enemies are defeated.
 * In one episode of Buffy the Vampire Slayer, Buffy ends up in an inescapable ambush when
 * That happened several times in season 4, including  and  . Also
 * Happens a lot in the Resident Evil series. Usually hand waved as some sort of security mechanism to keep in whatever viral beastie you are fighting. About half the time it's played entirely straight (the door opens when the enemies die), sometimes there's a variation (the door opens when you've done enough damage to the unkillable enemy), and sometimes it's subverted (you can--and have to--escape; you just have to survive long enough to do so).
 * Dead Space does this repeatedly. The computer warns you that infected entities are in your sector, all doors lock and you have to kill all the baddies to get them to unlock again. The justification is that the computer is futilely trying to stop the spreading of the infection, but you gotta wonder if a computer that traps everyone involved in an accident right where it happened, when "the accident" means "horrible possession by Face Full of Alien Wingwong", didn't turn a moderately serious infection into a shipwide disaster all by itself.
 * They have a few of these on one specific planet in Ratchet and Clank Going Commando. Notably, one of them only triggers if you open the health box.
 * This pretty much defines the enemy battles in Vivisector: Beast Inside; not only are you forced to trip an Inescapable Ambush each time you activate a checkpoint, during the first half of the game, but said checkpoint is usually situated in another cage that springs up, usually much smaller so you're literally a sitting duck for the enemies you're supposed to clear out to be released.
 * A side quest in Fallout New Vegas has the Courier exploring a Vault that had a "sacrificial chamber." Upon activating it, numerous robots literally come out of the walls and seal the chamber until they're all defeated.
 * The Metal Gear Solid series have these where a group of enemy soldiers corner you and you cannot escape, thus you're forced to fight them due to the plot.
 * In Vampire: The Masquerade Bloodlines you
 * There's also an optional mission where
 * Deus Ex's Alex Jacobson will not give you the key to until you have killed, if you have not done so already. It's a tough fight if you don't . However, the Mooks in the building can be avoided, the  is an instant win, and sequence breaking minded players can use the old "enemies have master keys" trick to avoid needing to kill her entirely.
 * Certain quests in the Dungeons and Dragons Eberron Unlimited MMO have rooms with portcullises that slam down when a player enters and don't open until the monsters (or players) inside are slain or a timer runs out. These are particularly annoying to anyone outside the room when this occurs.
 * The standard Hold the Line type finale in the Left 4 Dead series works a bit like this- your rescuer will often say over the radio that they're X minutes away, but the vehicle won't actually arrive until you've killed all the necessary enemies (a wave of common infected, followed by a Tank, then more commons, then a second Tank. Then a ****load more commons and multiple Tanks, but at this point you need to stop killing and run like hell)
 * Occurs frequently in Descent II, where doors lock or walls appear upon entering a room or taking a key, and Mook Makers or monster closets activate.
 * Also happens with many bosses in the Silent Hill series. The most memorable example comes from the second game - the door suddenly closes behind James in the preceding cutscene,  Obviously, he immediately tries to open it and run to the hills, but to no avail.
 * Knights Of The Chalice is very fond of this trope, you can barely enter a room without the door slamming shut and spawning a bunch of monsters right on top of you, and if you try to hug the walls or head for a corner the game will teleport you right into the middle of the room so you're always surrounded no matter what.
 * In some of the Ys games, you are locked into boss battles. Which means that if you're underleveled, you can kiss your ass goodbye. Hope you saved beforehand.
 * Dragon Buster did this with every single room.
 * Used all the time in Dragon Age Origins map random encounters, but a special mention must go to the.
 * Henry Hatsworth in The Puzzling Adventure uses these viciously, with nearly every level having one or two of these. The game usually uses these to introduce new types of enemies, or to just make the stages that much harder.
 * In Kid Icarus Uprising, every now and then Pit will get locked in a room and will be required to take on an onslaught of enemies in before progressing any further.