->''"You used your [[WarpWhistle escapipe]]! Normally a smart move, but now I'm afraid the game can't be continued. Please press the ResetButton and try again."''
-->-- '''The King''', ''PhantasyStarIII'', after you escape from prison [[TheDevTeamThinksOfEverything the unauthorized way.]]

Most kinds of games rely on a certain set of triggers and rules to regulate the progress of the scenario and check whether certain conditions are met. In addition to triggers and rules, there are also implicit assumptions about the state of the world - that certain entities are still alive, that the player cannot reach spot X without having done task Y. These are usually collectively known as the game's "script".

Often, particularly in games that allow a significant amount of free-roaming, if one attempts to do something that would make sense in the real world and/or within the game world, and that is technically allowed by the rules of the game, one will find that the game is not robust enough to cope and one will get stuck, be forced to go back or find that events play out in an illogical fashion. This typically happens by violating one of the assumptions about the state of the world. Killing an entity that the game needs later, using SequenceBreaking to reach location X without having accomplished task Y. And so forth.

It is also common to experience this if one cheats, particularly by trying to create a specific condition without the proper prerequisites having been met.

These situations often occur when the player tries to do things [[GameplayAndStorySegregation the scenario suggests is possible and even reasonable, but which the game rules cannot account for]].

See also ButThouMust and StupidityIsTheOnlyOption. For the idea of "breaking" a script in the writing process, see: ScriptLifeCycle. The polar opposite of this trope is TheDevTeamThinksOfEverything. Often coincides with SequenceBreaking, which deals with the intended sequence of gameplay elements rather than the logical cohesion of the narrative, since breaking one of these tends to break the other as well.
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!!Examples:

* The ''OperationFlashpoint'' single-player campaign features at least two instances of this:
** In one mission, the player character is captured [[SimultaneousWarningAndAction as soon as he reaches a particular area]]. It is possible to kill the enemies that do the capturing if one throws grenades into the area where they stand, in which case the cutscene will still play out, but the captors will be corpses lying still on the ground.
** In another mission, the player must attempt to slip a lorry full of partisans through an enemy control post. If one goes along with this, there is a scripted confrontation and one is forced to escape on foot while being pursued by enemies. Yet if one takes the lorry off-road before the control post, one can drive through the forest and reach the final destination without incident. At that point, the game's script forces the passengers to get out and head back to the control post on foot, to fight a skirmish that was supposedly undesirable.
* In the second-gen ''{{Pokemon}}'' games, using a "Walk Through Walls" GameShark code and walking up to sprites you are not supposed to touch will either make the sprites say "object event" or crash the game.
** The same thing happens in the first gen games too, and you can encounter some [[TheMissingno pretty bizarre glitch trainer battles]] with it. You can also break sequence in both Game Boy titles and get into pokemon battles without actually having any pokemon in your party, which also results in funky (and game-breaking) glitches.
* In the N64 game ''VideoGame/GoldenEye1997'', the player can have much fun by exploiting the cutscenes with a cheat code that gives Bond an unlimited supply of every weapon in the game. The player can stop just short of the area where a cutscene will activate, load the area with explosives, such as proximity mines, and then step into said area, resulting in a cutscene where [[OutOfTheInferno Bond will walk unscathed through an environment erupting in fireballs]] and sending any [=NPCs=] [[RagdollPhysics flying]]. Fortunately, this does not result in a mission failure if one of the [=NPCs=] killed was supposed to [[EscortMission stay alive]].
** Also, fiddling with the second player controller, with the addition of luck, one can simply shoot down many of the cutscene characters. Causing, in one instance, the memorable scene of Bond in his VictoryPose with his BondGirl Natalya dead at his feet.
** It's also possible to kill every named baddy in ''VideoGame/GoldenEye1997'', whether or not they are supposed to die at that point. Generally, though, you can only get away with killing Ourumov without failing your mission. Unfortunately, the storyline never changes.
*** Baron Samedi, in particular, can be killed in the ending cutscene of his level. ''During his maniacal laughter.''
* In ''Soldier of Fortune'', there are numerous instances where an enemy scripted to fall from a perch in a sniper's nest when shot can be shot by the player before he's in position, resulting in the enemy character displaying the "falling" animation anyway, even if he's already on solid ground. Some enemies can likewise be shot by alert players before the game intended, after which they calmly proceed to their next scripted checkpoint missing arms, legs, or even heads. Only upon reaching said checkpoint do they apparently realize their wounds and expire. It is also possible for a sufficiently skilled or determined player to snipe the pilot of a helicopter carrying a pallet of crates meant to take off and leave immediately after coming into view. If the pilot is shot in this very narrow window of opportunity, the helicopter crashes while the crates continue up and away.
* In ''VideoGame/DeusEx'', the player, attempting to escape New York by catching a helicopter in Battery Park, is met on his way out of the subway by an overwhelmingly large enemy force led by a character flagged as invincible. There are several ways to sneak around the group without being caught, but even if you get to the helicopter, you can't take off -- the game requires that you be captured. Earlier in the game, it is possible to go from a bar in which the pilot of the helicopter that transports the player is drinking to another area, complete the mission there, have him arrive in the helicopter for pickup, and through creative use of crates jump back over a fence and make it back to the bar, where the pilot can still be found. There's also various {{Boss Battle}}s that can be completely skipped if the player manages to kill his enemy before triggering the cutscene (usually by approaching said enemy) that initiates the battle.
** DX has been [[http://it-he.org/deus.htm hilariously, systematically broken]] by some of its more "devoted" fans.
** Subverted with Anna Navarre. The smartass player wanting to break the script by killing her before she starts her dialogue (by placing a mine on the entryway) will cause the game to [[TheDevTeamThinksOfEverything proceed exactly as you'd expect in the event of Navarre's murder]].
** Killing such people as Joe Greene and the caretaker before you're asked to results in JC Denton telling them he offed them already - Dowd and Philbin will remark that you're ProperlyParanoid.
* In ''VideoGame/{{Hitman}} 2: Silent Assassin'', it is possible to kill the final boss by strangling him with a garotte through a wall. If you do this, then the cutscene before the boss fight will show a shotgun floating in mid-air, and during the battle you'll fight the ''boss' flying corpse.''
** And if you strangle him after the boss battle start, he will be on the ground in a HUUUUUGE puddle of blood. The Dev team assume you would shoot him with the M60 or another really heavy gun.
* In ''BaldursGate'' a character called Biff the Understudy will appear to deliver the lines of characters that have been killed prematurely.
** Players quick with area-of-effect spells can kill two minor characters who set off an otherwise mandatory sidequest involving the main character being poisoned and needing a special antidote, preventing the quest from ever activating. Skipping the sidequest has no ill effect, and taking the pair out right away means that some good loot can be snagged a bit early.
* In ''VideoGame/HalfLife1'', near the beginning of the game, the player climbs a ladder to see two zombies fighting a security guard. The guard talks to the player upon seeing him. A particularly lucky and/or skilled player can shoot the guard to kill him as soon as he begins delivering his line, therefore causing the guard's corpse to speak.
** A more serious one occurs when Freeman gets captured. In older versions of the game, you may break the script if you try moving around during the cutscene, leaving you in a dark "script-holding" room which you can't escape from.
* Sequence breaking is possible in certain ''Franchise/{{Castlevania}}'' games. A glitch in ''VideoGame/CastlevaniaPortraitOfRuin'' makes it possible to enter a cutscene room from the wrong side -- in which case the scene still happens, but with you standing behind the bad guys, who don't turn around. The fact that there are ''gestures'' in this scene makes it even more surreal.
* In ''VideoGame/{{Zork}} III'', grues prevent you from going into dark places; this normally justifies the need for a lamp, but one place was blocked by a lake that extinguishes your lamp, requiring you to find Grue Repellent. However, in early versions of the game you could put the lamp inside a chest and take it to the area without being extinguished. Strange because the unintended, script-breaking activity also happened to be perfectly logical--of course putting the lamp inside something keeps it from getting wet.
* ''VideoGame/TheLegendOfZeldaOcarinaOfTime'':
** The game only checks for completion of two of the five "adult" temples. By abusing certain bugs, the savvy gamer can complete the Shadow and Spirit temples without completing the Forest, Fire or Water temples and then gain access to the final temple. The game assumes that you have completed the other three. It's also possible to beat the game while skipping all 5 temples by glitching items into your main hand and capturing stuff in bottles to overwrite the quest flags.
** That's nothing. With some clever glitching it is possible to beat the game, without ever becoming an adult, in ''24 minutes''. [[http://www.youtube.com/watch?v=VV0p9wFmMo8 See for yourself.]]
* In Chapter 2 of ''TheMagicOfScheherazade'' for the NES, you're supposed to fight through the Chapter, bouncing back and forth between the present and the past, going through caves with invisible pits, with the goal being to ultimately acquire a character who can guide you through the Maze Desert, a Lost Woods sort of area, to the Palace of the boss of the Chapter. Problem: The sequence through the Maze Desert is always the same, and the game doesn't bother to check to make sure you actually ''acquired'' said guide character, making it possible to skip most of the Chapter and go directly through the Maze Desert to the Palace. It's clear Culture brain never bothered testing this scenario, as the characters you skip by doing this show up in any post-Chapter cutscenes (But, oddly enough, not in the RPG battle sequences. In fact, you can't even select individual characters you acquire later in those sequences--you have to select their Formations; the game won't scroll past the "holes" created by the missing characters). Given the game is pretty good about checking for other breaks (The funniest "You can't do that!" message is probably "You don't have enough friends to defeat Troll"), this specific one is rather surprising.
* In ''StarWars: [[VideoGame/DarkForcesSaga Jedi Knight II]]'' if you kill Tavion not the usual way, by accumulating damage, but by tossing her off a cliff (ridiculously hard to do, because they were almost always immune to Force Push) the cutscene that plays afterwards, where Kyle is supposed to threaten Tavion, plays out as normal, except without Tavion. At one point, Kyle is suspending Tavion in mid-air with the Force Choke ability, thinks better of it, and drops her. At which point Tavion fell out of midair, back into the scene.
* In ''KnightsOfTheOldRepublic'', on a Light Side run through the Star Forge you encounter Bastilla a second time, which is supposed to be your opportunity to save her. You can choose instead to kill her, and the game will confirm her death in the usual manner... though it won't change the fact that she somehow shows up alive and well in the ending sequence.
* In the ''FreeSpace'' series of [[SimulationGame space sims]], events are usually triggered by the presence or the absence of a certain ship. To prevent ScriptBreaking, mission designers often make script-important ships invulnerable, or cause them to self-destruct if the mission doesn't go out as planned. The "fix" itself causes certain problems, for example, a player manages to immediately disarm an enemy capital ship that was supposed to destroy a friendly target, the friendly ship will ''still'' give out a mayday call and blow up ''anyway''. Other times, during an attack that's "impossible to repel", the invulnerable or self-destruct events are not included because the mission designer is confident that the script will go out as planned anyway. When the "impossible" event happens, and the player managed to fend off the three dozen GoddamnedBats and successfully defended the disabled friendly cruiser (that was [[BecauseDestinySaysSo destined]] to blow up), the mission just freezes. Or maybe the rebel cruisers that are "no match" for the gigantic GTVA Colossus get in its blind spot and [[DeathOfAThousandCuts slowly chip away at it until it blows up]]. ScriptBreaking in ''FreeSpace'' will have ship commanders talking from the dead, or from subspace, or the action just stopping and never getting the "Return to Base" order.
** In ''Freespace 2'', there's a mission where you're supposed to destroy some of the Sathanas' main guns to give the Colossus a fighting chance. It's possible to destroy ''all'' guns, which makes the next mission hilarious: The Colossus sticks to it's script and delivers paniced damage reports even if it's receiving ''no'' damage.
** There is also a slight subversion in Freespace 1 in the first mission where you encounter the Shivans. If you manage to destroy the Shivan ship that's supposedly out of your league, you'll get a medal and a special mention in the debriefing.
** Space sims in general have notoriously bug-prone objective systems, usually don't allow in-mission saves, and often change objectives in mid-mission or vaguely state mission objectives to begin with. This can lead to a lot of GuideDangIt moments where the player isn't sure if they're failed, succeeded, or if the game has bugged out on them.
* With the use of a cheat code in ''VideoGame/GrandTheftAutoIII'', a player can use cars as flying vehicles. If the player manages to master the controls of the vehicle, they can fly over the broken bridge that they start at in the beginning of the game, causing the script to completely skip the first third of the game.
** It's possible to skip the second island as well, with some creative use of boats (you can't get a boat over the pipes in the sea, but you can beach it and push it around on land... and back into the sea again).
** It's possible to cross the broken bridge immediately with some creative jumping (at least on the PC version), and if you ram a car into a moving subway train in the right part of the second island you can pop back up on the third island.
** This was averted in ''San Andreas''; there are several ways to get to the blocked areas, but since you can't buy any property or enter any shops, all you'll be doing is running from the cops.
* This happens in ''Phantasy Star 2'' if you kill the security bots coming to arrest you by cheating, after which you can no longer progress through the plot.
** This becomes far worse if you get afflicted with a glitch in which you get into a random encounter at the same time those things should attack you (win and you're stuck). Beyond frustrating if this occurs on a first playthrough.
* The infamous "Red Key Card bug" from ''LittleBigAdventure'' / ''Relentless'' is caused by ScriptBreaking. Normally, in order to break into the museum, you need to get said key card from a character and use it on the back door of the museum to get in and do some stuff here (including stealing several items). However, it is perfectly possible to steal these items by just fighting your way in from the front door, and if you do this, ''the game will assume you already have the key card, so you can no longer get it''. The nasty part is that ''you'll need the card later on and won't be able to complete the game without it''.
* In the final mission of the single player campaign in ''Age of Mythology'', you are supposed to get Arkantos turned into a demi-god and have him kill a statue of Poseidon. But if you're good you can just destroy the statue with your mortal army, at which point, sure enough, there's a cutscene of demi-god Arkantos fighting and finishing off the statue.
* The first-person-shooter ''RedFaction'' had rebel miners that were scripted to be killed by certain guards, either through grappling or general combat. Killing said guards before they could kill the miners (or were in the process of), would often cause the miners to grapple with 'invisible' enemies while the guards' corpse lay at his feet, or merely fall down dead when reaching the end of their script.
* Several first-person-shooters (including ''Red Faction'' and ''VideoGame/CommandAndConquerRenegade'') have [[AlmostDeadGuy dying allies who are scripted to deliver a message and then expire]]. Since these scripts are uninterruptable, the player character can freely whale on the dying soldier/medic/civilian/scientist with any weapons he has available, while the poor schmuck continues delivering his important dialogue. ''VideoGame/HalfLife1'' features a similar situation, with scientists and guards who are supposed to remain in sitting, lying, crouched (or otherwise immobile) positions (and usually deliver a Message Of Importance). When given a whack with the crowbar, they will ignore their previous script, stand up, and perform as any other instance would.
* ''VideoGame/TheElderScrollsIIIMorrowind'' is (in)famous for its many bugs. Being a sandbox game, the player can kill pretty much everyone. Inevitably, a main quest-critical NPC could be inadvertently killed by the player. Usually, killing an important NPC will display a small message indicating that the main quest is now unbeatable. However, many lesser [=NPCs=] do not display that message when eliminated (try killing members of the three houses, such as Dren).
** Averted in ''[[VideoGame/TheElderScrollsIVOblivion Oblivion]]''. Important [=NPCs=] cannot be killed, only temporarily knocked unconscious. While the game cannot be rendered unwinnable, it also lost much in immersion.
*** Bethesda made the main quest script more flexible, so that it can have multiple entry points. This allows experienced players to skip ahead of the hoop-jumping-intermediary-fetch-quests, or psychotic players to shoot 'em all as they go, but has surprised exploring first timers who weren't expecting to stumble back into the plot.
** User-created mods are sometimes plagued with "talk triggers" not activating. When the player is meant to be able to advance conversation with an NPC, they are given a "talk trigger" to ask something new. These can break -- by no fault of the player -- rendering the quest impossible to continue.
** In ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]'', it's possible for this trope to occur when first entering Solitude. [[spoiler:A public execution will be happening, and while it's possible to kill the executioner, the man to be executed still dies regardless. Most notable is that the man to be executed can get up and run away, only to drop dead with his head cut off moments later.]]
*** Funnily enough, they actually averted this in other cities: in particular, in Markarth, usually the first thing you see is an assassin stab a woman to death and then get taken down by the guards. If you're aware of this, you can kill the assassin before he kills the women, in which case she'll merely be flustered and the quest chain this event starts reacts to make the appropriate minor changes.
* At one point in the FPS ''VideoGame/ShogoMobileArmorDivision'', the player finds himself in an underground tunnel, where proceeding forwards will trigger a cutscene where an enemy appears, runs off, and causes the tunnel to cave in by exploding it. However, careful examination of said tunnel reveals a logo of Monolith (the game's creators), which when shot causes the same explosion, making the cutscene look totally wrong as a result.
* In ''VideoGame/HalfLife2'', at one point the player runs across a courtyard dodging fire from a huge disintegrator ray. When the player rushes into one of the buildings, they'll see a man behind prison bars get shot to death by some Combine. If the player is lucky/skilled enough and fast enough, they can kill the guards before they can kill the person behind bars. However, the NPC will crumple up and die anyway.
** If you do manage to kill the Combine in time, the man doesn't die right away. Looking through the door at the correct angle will reveal that he is still very much alive - until you walk through the door and trigger his scripted death. Instant ragdoll.
** Similarly in ''Half-Life 2'', at one point the player will come across two men, on a rock, one injured. A small little scene will take place and summon three Antlions at once. If the player is extremely lucky and skilled, they can kill the antlions when they pop up before they are able to do anything, but the injured man will die regardless. I guess one of "the greatest minds of our generation" can not be saved.
** Late in the game the player can carry a turret into a room where an NPC ally is being held captive. The turret is hostile to the ally, and will open fire. For some reason this NPC lacks GameplayAllyImmortality and can be killed by the turret, which prevents the game from advancing further.
* By using a collision detection error, it is possible to get a few Pearls earlier than you're supposed to in ''VideoGame/BeyondGoodAndEvil.'' This isn't script-breaking in and of itself... But if you hunt for all the Pearls possible at that point in the game, it ends up giving you ''just enough'' Pearls to purchase the next hovercraft upgrade, the Jump Booster, which you aren't supposed to be able to do until after you've been to the Factory area. If you attempt to go to the next area, the Slaughterhouse, without visiting the Factory, the game gets rather confused--dialogue for Double H appears, even though he's technically still trapped in the Factory, referencing events in cutscenes you haven't seen, and Pey'j mysteriously vanishes. If you make it through Slaughterhouse Road and attempt to dock at the other side, the game freezes up--presumably because it has no idea just who the heck is your partner anymore. [[http://www.youtube.com/watch?v=fEoHrHOGXkw&feature=PlayList&p=BEBF60EB7C4160A9&index=0 A video demonstration.]]
* In ''Maelstrom'', a rather poor and buggy sci-fi RTS, about the only interesting feature was terraforming : raising or lowering terrain. There were at least 2 moments were this could be used to screw with the game. In one mission the player had to move a group of units through a half flooded ruined city. The usual way was to use terraforming to create bridges between the small island in this area to go around and end up on top of a small cliff. Or, since the player had lots of energy resource, you could just raise a gigantic ramp to the top of the cliff from one of the first islands, bypassing a few event triggers and confusing this missions objective system. In another mission the player had to destroy a few alien bases in a mountainous region. The map was divided by a few mountain ranges with several valleys in them for ground units. Since the aliens have no terraforming or flying transports, the player could just raise walls in the valleys to cut of his part of the map from alien ground units.
* In ''Ecstatica II'', you were supposed to open the doors to the main hall by striking them with the rod retrieved from the top of the prison tower. However, it was possible to jump from the terrace above onto one of the balconies of the main hall and get in that way. However, you weren't able to get the doors open from the inside, and there were no other exits.
* It's possible to finish ''UltimaVII'', getting the last two prisms with script breaking, leaving Alagner alive and skipping the Time Lord.
## Trying to reach the square prism without protection subjects you to damage that eventually exceeds your maximum hit points. The Forge of Virtue add-on increases your maximum hit points but the programmers forgot to increase the damage done when you go for the square prism. Result: it's now easy to get the prism without protection if you heal yourself.
## The path to the round prism doesn't kill you if you don't have the needed items. It just sends you back. It turns out that repeatedly trying will eventually get you there anyway. This may have been an interaction between a fast machine and a slowdown program.
* An annoying one in ''FEAR'', though it got patched. There is one laptop in the entire game that is plot relevant, the rest are there for listening pleasure. The thing is, once you download the data from the laptop, you can't download it again. You also get to see this laptop and use it before said plot relevance is made. So when your CO asks you to download the data from the laptop, which you might've done already, you can't download it and complete the objective. Spend all the time in the world running around the map, but you'll just have to restart from your last save.
* In ''Champions of Norrath'', after defeating the Spider Queen Shelox, the player is supposed to enter the tunnel Shelox emerged from in a cutscene before the fight. If, instead, the player uses a Gate Scroll to return to the town to sell the loot Shelox dropped and then use the Portal in town to return to the Portal outside the bosses chamber, the player becomes stuck. The door into the chamber is locked for the fight and was originally unlocked during a cutscene by an escort character. There is no mechanism for the player to unlock the door from the outside, and Portaling back to town and using a Gate Scroll (hoping to return to where the first Gate Scroll was used, in the chamber) teleports you to the last place you were teleported...which is the Portal outside the lair. Time to restart from the last save...
* Crafty players can jump down very deep pits in ''Franchise/{{Halo}}'' to sequence break. However, more than sequence break, the player skips all the event flags in the map as well; Master Chief can trot to victory! Neither friend nor foe will spawn in the entire map due to the linear nature of Halo's event tripping.
** In ''Halo 3'''s The Covenant mission, landing the Hornet on the Citadel can prematurely trigger the next chapter, and when you reach the point where the Flood team up with you, the game freezes.
* ''{{Strife}}'', the ''VideoGame/{{Doom}}'' engine RPG, is painfully easy to break. From minor and recoverable things like going back to break the illicit power tap (and failing a mission you've already completed) to major things like killing the Sigil piece holders in the wrong order, which makes the game {{Unwinnable}}. There's only two 'official' sequences, one for the happy ending ([[spoiler:Programmer, Bishop, Oracle, Macil, Loremaster]]) and one for the DownerEnding ([[spoiler:Programmer, Bishop, Macil, Loremaster, Oracle]]), but you have access to two of the last four for the entire second half of the game and can theoretically kill them at any time. The game plays fine as long as you obey everyone's orders, but don't ever think for yourself.
* ''{{Stranglehold}}'' checks to see if you've beaten a section by crossing a trigger. However, it checks for ''any'' trigger. One those rare occasions where you can go backwards through the level, it is possible to advance by retreating.
* ''KyaDarkLineage'' is susceptible to this, at least if you're able to engage in any SequenceBreaking at all. For instance, in the final area (the Wolfen Lair), you're supposed to progress through the level and get captured by the Wolfen, who will take away your weapon. This may not seem like much, but it's actually damned important. It is possible to get through the blocked door, over the top, and sneak in the back way. Clever, right? Wrong. The game was not at all prepared for this, and will still trigger the cutscene wherein Kya is caged up and unarmed- at least in theory. In practice, retaining your weapon through this sequence break makes the game {{Unwinnable}}, as you then have no way of accessing the command you need to get out of the cage once the cutscene is done. Admittedly, SequenceBreaking is made far, far more difficult (supposed to be impossible, of course!) than in games that reward it, but to not anticipate at all that some player would try it is just silly.
* In the ''{{Starcraft}}'' mission "Agent of the Swarm" (the Zerg mission where you have to defend the Chrysalis until it hatches), normally you're supposed to wait until it hatches then infest a Terran Command Center, but there's nothing stopping you from just waltzing into the base and taking the command center as soon as the mission begins (although, through legit means it'll probably hatch before you get near the command center). This makes the conversation at the end of the mission weird since [[spoiler: Infested Kerrigan]] hasn't hatched yet but they're talking to Reynor as if they already hatched.
** In an early Terran mission, Raynor tries to stall a Zerg invasion until evacuation transports can arrive. Even if all the Zerg on the map are destroyed, the Terrans still leave at the end of the mission.
* ''VideoGame/ChronoTrigger'' encourages ScriptBreaking in the NewGamePlus to access many of the game's multiple endings, and can, in fact, legitimately allow the player to kill the final boss about 20 minutes after the introductory cutscenes. However, this does result in some bizarre dialogue before the fight, given that the party [[spoiler: may never have even seen the [[TheEndOfTheWorldAsWeKnowIt Day of Lavos]] video to begin with, let alone have learned what they know about Lavos]].
** [[http://www.youtube.com/watch?v=vU4vlzEdBpI Tool-assisted]] run of the whole game from the beginning show how the storyline can be messed up to the point of the plotline being a complete mess.
* In ''VideoGame/{{Fallout 3}}'', if the player picks Mr. Burke's pocket before telling on him, he will repeatedly try and pull his gun of Lucas Simms, and if the player follows Lucas out of the bar, he falls over dead anyway. Lucas can be saved via other means though (Such as taking the hits for him and taking out Burke).
** While perhaps not -script- breaking, it is possible to simply go to your dad's last location and do the final missions first. While this is a nice shortcut for veterans, a new player doing a certain side-quest will almost certainly trigger an event flag at around the half-way mark of the main quest, thereby accidentally side-stepping a huge chunk of the main campaign. It's somewhat immersion-breaking, at the very least. It's also awkward if you want to get all the achievements.
::: It's also pretty easy for a new player exploring the Wasteland (rather than following the main quest) to stumble upon his location, which doesn't even have a locked door to keep you out of it.
** On the other hand, if you do choose to break the sequence and skip meeting Three Dog, you can still go back and do his quest, and [[TheDevTeamThinksOfEverything the reward changes to the location of a weapons cache]].
* In ''TheLegendOfZeldaMajorasMask'', you can do this after you defeat a dungeon boss. You reset time back to the first day and warp straight to the dungeon and then the boss, after which characters who shouldn't remember who you are will act as though they've always known you. (However, this GroundhogDayLoop is a major feature of the game; once you solve certain quests and attain certain rewards, they stay solved and you keep the PlotCoupon even if you reset the clock again.)
* In the original ''VideoGame/PaperMario'', using a hack to defeat Bowser during the [[HopelessBossFight unwinnable boss battle]] at the beginning will not only be script breaking but will break the rest of the game [[http://www.youtube.com/watch?v=B61rOhq0x4A]].
* Players using the Mission Architect system in ''CityOfHeroes'' can learn first-hand what the developers have to go through to make sure that missions work properly, especially when trying to get fancy with chained objectives. If the script is not planned out well and tested it could end up making a mission near, if not actually, impossible to complete. The author needs to learn to [[TheDevTeamThinksOfEverything think of everything that their players might do.]]
* In ''VideoGame/CaveStory'', you can actually get past Chaco's house in Grasstown without getting the Fireball by getting hit by a bat at a specific point in your jump, giving you recoil that is just enough to get on top of the house. However, doing so gets you stuck since not getting the Fireball makes it impossible to get the jellyfish dialogue from Chaco which makes it impossible to get Jellyfish Juice which makes it impossible to advance the plot.
* In the free web game ''Realspace 2'', there is an opening cutscene of the enemy ships attacking a smaller set of good ships and then they attack the planet the good ships protected. The trouble? Not all events were actually scripted. The game simply spawned the necessary number of ships and had their AI's battle. But once in a blue moon, the good guys overcome the odds, destroying every enemy. The game stops there, the rest of the events never happen. Luckily this was an intro that could be skipped so the game didn't break. Notable for not requiring the player to do anything for this to occur.
* In ''VideoGame/EarthBound'', it's possible to glitch through certain walls and walk directly to any location in the game. At some points, the game assumes certain characters are in your party whether you've met them or not (even if Ness is alone when he's captured in Threed, Paula appears when Jeff rescues him; Poo appears when Ness returns from Magicant). However, you can't simply walk through walls to the final boss; you have to use the Phase Distorter to reach his location, or the scripted end of the battle won't trigger.
* In ''RedDeadRedemption'', you can get into Nuevo Paraiso and West Elizabeth well before you should be able to. The initial methods, which have since been patched, were camping on the New Austin side of the middle bridge to Nuevo Paraiso and camping on a very specific spot on the New Austin side of the river dividing New Austin and West Elizabeth to get into West Elizabeth. After they were patched, people found you could still get to West Elizabeth by getting arrested by the police in a spot that the game considered part of West Elizabeth but was actually in New Austin. After THAT was patched, people found out yet another way of getting into West Elizabeth; by riding a stagecoach down the hill near the broken bridge leading into West Elizabeth and aiming for the river, you could sail across to the other side. And people found out that it was then still possible to get over to Nuevo Paraiso by standing on the very edge of the aforementioned bridge to Nuevo Paraiso, shooting anyone you could see in Nuevo Parasio to rack up a bounty in Nuevo Parasio and then racking up enough for the police to get close enough to arrest you and take you into Mexico. There's not much to do besides buying properties and doing challenges, though.
* During the hospital escape sequence in ''VideoGame/MaxPayne2'', there are a couple occasions where hospital security is gunned down by the cleaners before the player can, theoretically, take action, but if through cheating or just sheer skill the cleaners are killed before they can shoot, the hospital security will just drop dead where they're standing anyway.
* An odd and semi-famous example: in ''VideoGame/CallOfDuty: ModernWarfare'', if the player turns on an infinite ammo cheat and scores a direct hit on the Hind that's chasing the truck (something that's impossible to do in normal gameplay), the ending changes. During the final scene where Zakhaev appears, a friendly NPC inexplicably gets off the ground and kills all three of the Ultranationalist soldiers with melee attacks before standing around as the Loyalist helicopter blows up the Hind behind him. Depending on when this occurs, Gaz will sit up and fall back down (even though he wasn't shot in the head), and when Soap receives the gun, there are no enemy targets to fire at - Soap puts the weapon down a few seconds later.
** In ''[[VideoGame/CallOfDuty Call Of Duty: World At War]]'', on the Vendetta mission, by performing a series of very simple jumps after the sniper duel, you can reach the area where Amsel is later on in the mission. There are invisible triggers all over the place which spawn soldiers, trucks and Amsel. By going through the triggers in a certain order, you can get Amsel to appear. This makes getting the achievement for [[CherryTapping killing him with a pistol]] a LOT easier.
* A minor-but-amusing case in ''VideoGame/FinalFantasyV''. Normally, the first time you enter the Sealed Castle in the second world, Galuf will explain to you exactly what the Castle is all about. It is never required that you visit the Sealed Castle in the second world, and if you put it off until [[spoiler:Galuf dies]], then [[spoiler:Krile will explain everything Galuf does, in the exact same way Galuf would have, and the text even will be credited to "Galuf".]]
* In ''VideoGame/FireEmblemTheSacredStones'', you can instigate some support conversations that refer to characters that haven't joined. A few of these were actually just translation errors though.
** Similarly, in ''VideoGame/FireEmblemBlazingSword'', you can have supports refer to events that haven't yet happened, most notably in Matthew and Serra's level A support, in which [[spoiler: Matthew is still grieving over Leila's death]], but the conversation can be triggered before [[spoiler: Leila dies]].
** Avioded in ''Path of Radiance'', where supports are now based off the number of chapters both partners are deployed in, as opposed to amount of turns standing next to eachother. Probably the main reason for this is Jill, who has most of her A supports refering to [[spoiler: the death of her father]], which doesn't occur until a specific chapter. Her supports are rigged so those conversations can't happen before said plot event.
** In ''VideoGame/FireEmblemAwakening'', Paralogues 2 and 4 involve a mini-arc with ThoseTwoBadGuys Vincent and Victor. You fight Vincent in 2, and Victor seeks to avenge his death in 4. Except Paralogues can be completed in any order, meaning it's possible to do the latter first...
* Spectacularly subverted in the indie game ''Iji''. At one point, [[spoiler: Asha sets up an ambush using Dan as bait. Normally, a Komato trooper teleports behind Iji, who kills the trooper and then Asha kills Dan while she's preoccupied]]. If you already know that this is going to happen, [[spoiler: you can place a mine you got earlier in the level to deal with an entirely different situation on the teleporter, killing the trooper on arrival while Iji just continues to point her gun at Asha's head and [[ProperlyParanoid tells him she's nobody's fool]]]]. [[TheDevTeamThinksOfEverything The game has an ''entire script lasting the rest of the game'', and even a variant ending, for this specific event!]]
** In fact, for an "innocent" run, ''0'' kills, you have to do just that. You can also do other script breaking things, which are rationalized by gameplay or story reasons, and there are events for that as well. The script refuses to break.
* The PC strategy game ''Dogs of War'' has no AI. Enemy units always move according to a preset script, so any deviation by the player from their expected behaviour will result in a script break. It is quite possible to see enemy units walking straight past your entire army because they are preset to go to a particular point at a particular time.
* On the Amiga ''Robin Hood'' game, killing the Sheriff of Nottingham causes the enemy guards to barricade themselves in their castle, where they cannot be attacked. However, Robin can enter the castle anyway by standing on the drawbridge at the exact time Maid Marian is crossing it. Doing so causes the guards to become confused, repeating they they must barricade the castle while they are already in it; and, in particular, if Robin is caught in the castle, the guard will forget that the Sheriff is dead and drag Robin over to the Sheriff's desk to be sentenced, then act surprised that the Sheriff is missing.
* ''Lego Batman 2'' has a number of these:
** In one case in a mission near the end of the game, the required exit to the next area is through a stopped fan. However, switching to Green Lantern and flying through the fan will leave Lantern stuck inside the area where the scene exit is supposed to be, but without triggering the exit.
** Some of the villains in Gotham City become strangely invulnerable if you switch to a character who is not appropriate to be fighting them. For example, Harley Quinn is completely immune to all of Superman's attacks, and can only take damage from Batman or Robin. Also, sometimes a villain can be pushed out of the location where they're supposed to show up, leaving the game confused and failing to start the encounter with the villain when they are approached.
** If you partner a character with flying or other special movement powers with one who lacks these (eg, Superman and Lois Lane), then travel a long distance across the map, the game will teleport the less mobile partner to you. However, in some cases it will teleport them to a location they were not supposed to be able to get to, such as inside a closed door that was supposed to be opened via a switch. Switching to them then allows you to continue the game from the unreachable location, possibly switching them out for a more capable character.
** Some of the buildings in Gotham City feature involved platforming sequences, many of which can be bypassed by using a flying character.
* in the Interactive Fiction game ''Dead Cities'', the game begins with the player bringing a book to be examined by a scholar, who talks about the book at length. In some versions of the game it is possible, at the correct moment, for the player to snatch the book back out of the scholar's hands and then leave the room while he is still talking. The player can then put the book anywhere in the house, but if they return to the scholar's room, he mysteriously has the book again.
* ''[[http://playfic.com/games/BlueInk/drying-up Drying Up]]'' is a very simple Interactive Fiction game; there are two necessary rooms, one item, and you can win the game with two commands. The first command, 'north', and the item (a cupcake you're supposed to eat) both knock you out and cause you to wake up in Town Hall. A playtester found that picking the cupcake up instead of eating it and going north allows you to eat the cupcake later and teleport back to Town Hall, causing an NPC to repeat a cutscene nonsensically. The author couldn't believe there was a broken sequence in such an impossibly simple game.
* ''Dishonoured'' has a hilarious example which occurs if Corvo exposes the Lord Regent's crimes after rewiring one or more of the "Wall of Light" security devices in his mansion to attack the guards instead of Corvo. The guards arrest the Lord Regent and begin to follow a script of marching the Lord Regent through the mansion to the exit and to prison - but their route takes them through one of the rewired Walls of Light, meaning they lead the Lord Region into it and watch him get incinerated in front of them.
* ''ArxFatalis'' has a PuzzleBoss that requires two steps to kill. A fast player can actually perform the second step before the first, which removes the boss as a threat but the game does not acknowledge the boss as actually defeated. Players thus miss out on substantial experience for the kill, and missing the first step may close off areas that need to be explored.
* ''VideoGame/QuestForGloryI'' (at least the VGA remake) unsubtly parodied this. If you find brigands' messages and try to give them to the sheriff, the game displays a message "Oops. You did something that we did not expect. Whatever it was, it is not required to finish the game." and the game quits.
** There is a similar joke in ''VideoGame/SpaceQuest 4'' in-game hint book.
** Similar messages, but requesting to file a bug report, were frequently displayed in beta versions of Sierra "Quests", when a player entered a legitimate command that did not do anything.
** The "oops" message is actually a debug message built into the Sierra game engine, and occurs when the game's script file does not specify a way of handling the command the player entered - script breaking in every sense of the word.
* In the Infocom adventure game ''Suspect'', the player encounters Veronica in fancy dress at the start of the game, before her death. However, [[spoiler:the woman is not really Veronica but the murderer's accomplice, creating an alibi for him]]. To prevent the player discovering this, if the player tries to follow Veronica out of the starting area, a slapstick cut-scene involving the butler is played out in the corridor which prevents the player moving to stay in pursuit. However, if the player does nothing else but attempt to move, they can still enter Veronica's office a turn before they are supposed to be there, which results in Veronica being nowhere to be found for that one turn, after which her dead body spawns from nowhere inside the office!
* In ''Franchise/StarWars: Rogue Leader - VideoGame/RogueSquadron II''[='=]s penultimate mission, [[Film/ReturnOfTheJedi Battle of Endor]], the mission starts with the Rebel fleet, you (as Wedge) included, flying towards the Death Star II. After a little time passes, Lando finds that the Death Star's shield is still up, and thus orders a turnaround of the entire fleet, only to discover the Imperial fleet behind them and to get ambushed by squads of TIE Interceptors. First-timers without prior knowledge of the mission and those who want to recreate the film faithfully will play along with this sequence of events, but those aiming for Gold Medals, speedrunners, and impatient players can simply turn around at the very beginning of the stage to make the [=TIEs=] show up immediately.
* Portal 2 contains some very subtle tweaks to avoid script breaks. The most obvious is that the color of the very last portal you shoot in the game is ignored.
** It's possible to break a script in Chapter 9. There's a sequence where you are supposed to use a funnel to escape a room, only to get attacked by a crusher. You're then supposed to [[spoiler: replace your portal onto a panel that shows up and get taken into an alcove]] But it's possible to jump into the alcove and watch as the crusher just stops.
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