Serendipity Writes the Plot

A Sub-Trope of Real Life Writes the Plot.

Either a plot detail, or even the entire plot is formed due to a technical difficulty in real life. Perhaps budget cuts prevented a certain aspect of the work from being filmed/programmed/drawn, or perhaps at the time, technology wasn't advanced enough, or some other limitation to create the feature existed. Whatever the reason, the creators are forced to compensate, and alter the plot to accommodate the limitation.

This is an interesting trope in the development of works. If it is done right, it can lead to an interesting plot, iconic appearance and/or an interesting feature of the work itself that would have never been achieved had the creators had the means to go with their original plans. If it comes out badly though, it will just give the work a very cheap look.

Can sometimes go hand in hand with Insurmountable Waist-Height Fence, as this trope is usually a reason for it. Is usually used to justify Graphics Induced Super Deformed in video games.

Related to Reality Subtext. Compare Ascended Glitch, Throw It In.

Film - Animated

 * The limits of CGI regarding the depiction of organic shapes and natural surfaces is the reason Pixar's first feature film was about toys. As the technology improved, they worked their way up to bugs, then furry/scaly monsters, then fish, and finally, human beings.

Film - Live Action

 * Low budget horror movies with no-name stars lead to Anyone Can Die. Alien may be the best known example. A cast filled with great character actors, but none of them are a big enough star to guarantee their character's survival.
 * This trope is touched on in the classic black and white movie, The Bad and The Beautiful.
 * A horror movie producer couldn't afford decent special effects for the monster. He teams up with the director to use camera tricks to make the monster into The Unseen.
 * From the trivia in the movie's IMDb entry, "The scene showing the production of the fictional low budget horror film was based on how Val Lewton produced Cat People (1942)."
 * Steven Spielberg couldn't get the mechanical shark in Jaws to work very well, so it became mostly The Unseen, with the entire concept of the sailors using barrels to track it as a way to keep filming as though the shark was there. The film is widely credited as working far better because of the increased tension and the greater impact of scenes where the shark actually did appear.
 * Hooper was originally intended to die in the screenplay. However, some footage captured by Spielberg's secondary crew, of a real great white attacking a visibly-empty diving cage, was so awesome that the plot was changed to let Hooper slip out of it safely, allowing them to use the shot.
 * Originally, Godzilla was going to be rendered via claymation for the original 1954 film Gojira. However, due to budget and time restraints, he was portrayed in classic People in Rubber Suits fashion and has been so ever since.
 * In the climax of the film version of From Russia with Love, villainess Rosa Klebb was fighting James Bond using a poisoned shoe knife. The script called for her to be accidentally killed by her own weapon, but the director couldn't figure out a way to film it that didn't look ridiculous. Then someone realized that a) there was a gun on the floor from when Bond had disarmed Klebb and b) the heroine, who had been an enemy agent recruited by Klebb before falling in love with Bond, was just standing there watching the fight. So the director changed the script to have the heroine pick up the gun, and after some hesitation, shoot Klebb.
 * In the Raiders of the Lost Ark, the scene with the swordsman involved Indy disarming the man with his whip. But Harrison Ford was sick with dysentery at the time, and asked if he could just shoot the man, which the final cut had him doing.
 * The opening of Spy Kids 2 was originally meant to take place at Disneyland. However, Robert Rodriguez discovered that Disney generally doesn't allow movies to shoot in their parks, not even Disney movies (note: The original Spy Kids films were distributed by Miramax Films, which is owned by Disney, and released under the Dimension Films name). This led to the scene instead taking place at a fictional amusement park with humorously impossible CGI rides. Rodriguez thinks this is mostly an improvement, although he still would have preferred it if Carmen and Juni had appeared undercover at the park wearing Mickey Mouse hats, but they had to settle for propeller hats.
 * Funnily enough, though, the finished film still has Carmen saying the line, "No more Mickey Mouse assignments" when she's annoyed at getting stuck with a mission at an amusement park.
 * The scripted climax of Back to The Future called for Marty to take the DeLorean to a Nevada nuclear test site and return to 1985 using the power of a nuclear blast. This was beyond the film's budget, so the now iconic clock tower climax was created.
 * Crispin Glover's refusal to do the sequels impacted the plot heavily. For example, George McFly being dead in 1985-A was originally conceived as just an excuse to not show him very much.
 * A prolonged chase scene in a Hall of Mirrors had to be cut from 1994's The Shadow after an earthquake shattered most of the prop mirrors on set. A CGI scene of the hero  was used instead.
 * The opening of Close Encounters of the Third Kind was originally scripted to take place in The Amazon with Lacombe's team finding the airplanes in the center of Crop Circles. This was too expensive and it got changed to a desert so that the sequence could be filmed near Los Angeles.
 * In Clerks, some local hooligans jammed gum into the locks of the convenience store's giant window shade, forcing Dante to make a huge sign that said "I ASSURE YOU WE'RE OPEN!" This gag is one of the film's most iconic images. But the truth is that the film was so low-budget that Kevin Smith could only shoot in the store at night, when the store was closed. Having the shades permanently down was a way to disguise the fact that it was dark outside during the daytime interior scenes.
 * The sequence in The Fugitive where Kimble loses his pursuers in the confusion surrounding the St Patrick's Day Parade was added to the script after the filmmakers realised that their scheduled dates for location filming in Chicago included the day that the real-life parade would be held.
 * In the first Tomb Raider film, the amphibious duck vehicles in Siberia were included in the movie because the director thought they looked cool. Similarly, the procession of monks was not written in the script, but the procession happened to take place as they were filming and the monks consented to appearing in the movie. In the second film, most of Lara's outfits have long sleeves, because the concealing makeup used to hide Angelina Jolie's tattoos in the first movie was not as effective as the filmmakers would have liked.
 * The 1941 biographical film Sergeant York has York capture and use a Luger instead of the 1911 he used in real life because .45 ACP blanks were difficult to use. The problems with .45 ACP blanks would actually persist in the film industry over half a century up till the end of the 1990s. The problem would typically be solved with the use of a 9mm copies of .45 ACP firearms (e.g., Magnum, P.I.) but Sergeant York was one of the few to change the plot over this.

Live Action TV

 * Some TV shows do "Bottle Episodes" due to budget limitations.
 * One episode of Friends did one about the NYC blackout because of budget constraints.
 * Not quite. Although it was a fairly low-budget episode (mostly pre-existing sets, and only two additional actors), the blackout gimmick was part of an NYC blackout storyline running through one night of NBC programming. The characters in Mad About You knocked out the power, and characters in Friends and one other show (can't recall which one right now) suffered through it since those shows were all set in New York. The Seinfeld folks wouldn't play, though. A better example of this in Friends would be "The One Where No-One's Ready", which, with the exception of the credit sequence, takes place entirely in Monica and Rachel's apartment and features only the main cast. Even the final scene is in a very uncomplicated set with only one additional actor.
 * Star Trek: Originally, going down to the planets involved the crew boarding a shuttle and flying down, but the cost of doing landings would have been too expensive, thus, the transporter was created. (Years later, members of the writing staff admitted that they had completely overlooked the even simpler expedient of writing "Send down a team!" followed by a Hard Cut to "Here we are, on the planet".)
 * Inverted with the flat forehead Klingons. Because of low budget, Klingons only had a mostly ethnic makeup in the original series. In the movies and later series, which had better budgets and better makeup technology, they obviously had the ridged foreheads. In Enterprise, a Prequel to the Original Series, they actually make a storyline to explain the change.
 * Played straight with the model used to depict Romulan Warbirds in the original series. A technician apparently dropped the model before filming, and there wasn't time to fix it or come up with a new one, so they used the Klingon Warship's model instead. This led to the conclusion that Klingons and Romulans formed an alliance, with warships sent over to the Romulans and cloaking device sent to the Klingons. Consequences of this action influenced the storyline of the entire franchise forever.
 * Star Trek: Deep Space Nine had this, with the character Dax. Jadzia Dax was a "joined species," an alien who was actually two entities sharing one body. Both entities (Jadzia, the "host," and Dax, the "symbiont") were intended to remain on the show for the entire run, but Jadzia's actress Terry Farrell left the show. The writers killed off Jadzia, but kept Dax, and gave it a new host, Ezri. The suddenness of Jadzia's death and Ezri's arrival worked greatly into the storyline, with Ezri Dax's main conflict being her having to form new relationships with people who'd already been her (Dax's) friends, and in Worf's case, husband.
 * Doctor Who: The TARDIS was originally going to be a big, magnificent vehicle. Except the show lacked the funding, so they said that it can disguise itself as anything it wants. Then that turned out to be too expensive they broke the chameleon circuit, so it stayed as a police call box.
 * In the original script of "The Brain of Morbius", Morbius's new body was cobbled together by his devoted robot servant. But it was the cheap story of the season, so they couldn't afford a robot costume as well as Morbius's body. So it was heavily rewritten to make the robot a human mad scientist (brilliantly played by Philip Madoc, resulting in a classic story).
 * While not a technical difficulty, during series 3 of Red Dwarf, Chris Barrie had complained that between his character on that show and the one in The Brittas Empire, he was suffering from "git overload" and desperately wanted to play someone heroic and likable for once. The writers took that desire and turned it Up to Eleven by creating "Ace" Rimmer.
 * Jane Leeves' second pregnancy on Frasier came at the perfect time, plot-wise, for Niles and Daphne to have a baby—in the final season, just ahead of schedule enough for Daphne to give birth
 * The Sarah Connor Chronicles originally was going to have a massive fight scene between the FBI and the central antagonist of the first season, a Terminator called Cromartie. When the budget turned out to be too low for it, the writing team got creative. This resulted in a chilling, minimalistic sequence where Cromartie slaughters the FBI agents (mostly off-screen) and tosses their bodies into the hotel swimming pool. All while Johnny Cash's "When The Man Comes Around" plays...

Sports

 * James Naismith, a physical education professor at International Young Men's Christian Association Training School (the YMCA today) was looking for a pair of boxes for the game that he had just recently invented. When he asked a worker at the Y for some boxes, he was told that they didn't have any, but he did have some old peach baskets lying around that could be of some use. The rest is history.
 * Some historians believe the rule to stop the clock on an incomplete forward pass in American football came because in the early days of the sport, games had only one ball and an old man for the official, necessitating the stoppage while the ball was retrieved.

Video Games

 * In City of Heroes, you could not initially wear a cape. In real life this was because the developers couldn't figure out how to implement decent cape physics. In-game, the explanation was that new heroes could not wear capes out of respect for Hero 1, who went on a suicide mission to stop the Alien Invasion that wiped out the beta. The city representative eventually would give a mission where you could read the history of Hero 1 and visit his memorial. Upon completion you got the option to wear a cape.
 * By the time City of Villains arrived this was a bit of The Artifact. But Lord Recluse will not let you wear a cape until you proved you were bad enough to go to Paragon City, smash lots of property, take out a chunk of Longbow, beat up a hero and take his cape for yourself.
 * In Sonic 3, there are a few glitches that could get Sonic stuck in a wall or otherwise trapped in, forcing the player to have to reset the game and start the stage over. The testers apparently found these glitches after the team had no time to fix them, so the instruction manual says that Dr. Robotnik placed undetectable traps that the player must bail Sonic out from by resetting the game.
 * Fog in video games is usually done because it would be very difficult, or even impossible, to render an entire area all at once. In order to make-up for it, the developers will usually Hand Wave it in some way. Some examples:
 * Superman 64 infamously Handwaved its poor draw distance (a result of both the N64's limitation and terrible programming) by saying that there is "Kryptonite Fog" all over the city.
 * A similar example (if better executed and received), Silent Hill's fog was originally there to cover up the graphical limitations of the PS. This helped the game's atmosphere so much that the fog (or sometimes snow) was retained long after technical improvements had obviated the need for it.
 * Spider-Man for the PS used the fog as a major plot point. The sequel got around it by having all the rooftop levels at night or dawn.
 * Grand Theft Auto III has heavy fog that just adds to the overall aesthetic of 'Crappy New York-esque city'.
 * The gas zombies in Dead Rising 2 are accompanied by green fog because it makes it easier to render the increased amounts of zombies.
 * As indicated above, multiple disc games often make certain areas inaccessible after certain points in the plot, to save on space on each disc. Each disc usually has some big event occur at the end of the disc that will remove access to certain side areas that are no longer useful to the plot in the next disc. It's annoying if you needed a certain item for a side quest, but allowed the developers to not have to try and fit the entire world and everything in it on the last disc, freeing them up some space for ending cutscenes, boss data, and the very definitely final dungeon.
 * Deus Ex: The Unreal Engine would not have been able to handle a fully rendered city with 2000 technology, forcing the creators to Hand Wave the boxed-in sections in the New York levels with a justification that due to high crime rates, authorities have walled in ghettos and other undesirable areas. In Paris, the boxed-in city is justified with the nation being on lock-down due to terrorist attacks.
 * A very eerie example was the lack of the World Trade Center in the New York Skyline. Due to memory limitations, the sections of the skybox including the World Trade Center had to be removed, and the creators justified it saying that they had been destroyed in a terrorist attack before the game started. Keep in the mind that the game came out in 2000.
 * A Game Mod of the game, The Nameless Mod, boxes its cities in as well and justifies it with a mention that Forum City is on lockdown due to one of the moderators being kidnapped. The maps are bigger than Deus Ex's were, but you can see why the boxed-in method was needed if you "noclip" yourself away from the map and try to view it all at once. It can lag or even crash the game.
 * Deus Ex: Invisible War: The final level at was frozen over and much of it cut off due to the fact that the console version of the game would not be able to handle swimming and larger maps. The map size is true of every level (though isn't as blatant because they are all new otherwise) and such limitations due to console hardware are always cited as the game's reasons for failing and hatred from the fanbase.
 * Donkey Kong: The original arcade game had a chubby, mustachioed Mario (then known as "Jumpman") wearing a hat and overalls due to technical limitations. The technology at the time would not have been able to show Mario's hair sticking up when he fell, a mustache would be easier to show than a mouth at that resolution, overalls were the only piece of clothing that could also been seen with 1981 graphics, and only square hit boxes were possible. These same traits would latter come to benefit Mario again in his Nintendo 64 outings, which have aged considerably better than other early 3D games as a result.
 * One of the key traits of Space Invaders is how the aliens get faster as you destroy more and more of them. This was originally an unfortunate consequence of the low processing power being choked by the large number of enemies, but the creators liked it and decided to keep it in.
 * Probably one of the reasons games that were set in space were probably so popular in the early days of video games was how easy they were on both the part of the developers and on the hardware they ran on. Black screen with occasional white dots is very easy to draw.
 * Due to technical limitations, the early Resident Evil games had a loading screen for each area. The designers took advantage of this by making the loading screen the animation of a door opening. The door, in fact, that the player was entering through.
 * In Resident Evil Code: Veronica X the developers tried to manufacture this tension, with deliberately delayed door openings accompanied by thudding heartbeat sounds and throbbing rumble controllers.
 * The first Dizzy game made use of an engine for rotating sprites in real time, allowing the hero to roll and tumble. However, the engine worked best on simple shapes, such as circles - and thus, Dizzy became an egg.
 * In Kingdom of Loathing, after a bug involving an item that took meat away from players (coupled with the ridiculously high Cap for meat) screwed up the game's economy, a number of "meat sinks" were introduced to deal with the "bug meat", including the Penguin Mafia and the various goods they offered. Much later in the game, a database error that wiped out several days' progress for many players lead to the introduction of a "Time Arc", in which portals through time started opening up throughout the kingdom.
 * In the Monkey Island games, Stan has an Unmoving Pattern pattern due to technical reasons in the first game, but it has been kept, even after the series became full-3D (and it required extensive effort to replicate under the conditions) and becoming a plot point in Tales, simply because it is so iconic of Stan.
 * With Metroid, the iconic Morph Ball came into being because the programmers had trouble making an animation of Samus crawling through small passageways. Thus, they made do with a much simpler animation of a rolling ball.
 * Star Fox's iconic Arwing fighter design was conceived largely because it could be made out of relatively few polygons. In addition, the "fly into the screen" approach was used because of the SNES's strength at drawing 2D backgrounds, further conserving limited processing power. Full details are provided in this Iwata Asks interview.
 * In Dragon Age Origins, none of the Qunari had horns although their race is supposed to have them. This was because BioWare didn't have the time to create alternate designs for all the helmets just so your Qunari party member could wear them, so they opted to not give him horns at all and Hand Wave it by saying that Qunari born without horns are considered to be destined for greatness, while those who choose to leave the Qun cut off their horns as a way of showing their rejection (all the other Qunari in the game).
 * The miasma in Final Fantasy Crystal Chronicles is the driving force of the entire game, but it was originally just designed to keep the whole team on screen at all times. Your party has to carry around a chalice that wards the miasma in its radius, and leaving the ward causes you to take damage, so nobody can wander off, so split-screen isn't necessary, so everyone gets to enjoy Scenery Porn.
 * Q*bert and his enemies were supposed to speak in full English. However, the Votrax speech synthesizer used made things sound almost unintelligible, so this was changed to a sort of alien language that gave Q*Bert his famous profanity. The only distinguishable sound is "bye-bye" when you get a game over.
 * In the Legacy of Kain series, the second game Soul Reaver was much larger during development, which lead to it being an Obvious Beta. Among other cut content, Raziel's final brother Turel would have been fought, the Human Citadel would have been non-optional and contained a hidden area where the vampire worshipping humans lurked, and the ending was entirely unambiguous, Raziel successfully killing Kain and then activating the Silenced Cathedral to destroy every Vampire in Nosgoth. But the team was running out of time and there was only so much room on the disk, so a lot of content was cut and left out to be included in future games. A definite case of Tropes Are Not Bad though, because the series would go on to have an amazingly complex Kudzu Plot centering on Kain and Raziel's trips through time, and likely would have been nowhere near as successful and certainly not as deep or memorable if it had ended with Soul Reaver.
 * In the original Prince of Persia, the game developers wanted to add another character; however, space on the game floppy was limited, and a new character could only be created if it was a Palette Swap of an existing one. After tinkering a bit, the development team came up with a dark copy of the Prince: the Shadow Prince. This later became central to the game's plot, as
 * The ending of Saints Row, and the plot of the second game by extension, was changed when a "look at watch and walk away" animation was accidentally used instead of a "desperately running away while injured" animation. This resulted in a complete change to in the game's ending that was kept.
 * The name of the franchise, which previously used "Bling Bling" as a placeholder, comes from an early prototype that lacked a proper introduction, making the first thing seen a loading screen that said "Entering Saints Row", as Saints Row was the starting location.
 * Tak Fujii (Yes, that Tak Fujii) didn't bother to tune his guitar when recording for the song The Tragic Prince in Castlevania: Symphony of the Night's soundtrack (something he regrets as "lazy"). The result gives the song a distinctive atmosphere of horror that isn't present in future incarnations of the track.

Web Comic

 * The webcomic Bob and George is made of this trope. Originally the comic was supposed to be a hand drawn comic about teenage superheroes. The Mega Man sprite comics were originally just filler material. However, the author, Dave Anez, was a self admitted lousy artist and the hand drawn comic wouldn't pan out. After trying and failing multiple times he gave up. By then the "filler" sprite comic had become so popular that it became the main comic and a storyline was written to bring the title characters into the plot. Subsequent storylines would frequently change direction in order to fill in plot holes.
 * Another prominent example is the existence of the Helmeted Author. Originally it was meant to be the normal Author character who was now wearing a helmet because it was impossible to render a helmetless sprite in certain positions. However Dave later accidentally put both the normal and Helmeted Author sprites in one holiday comic. As a result the Helmeted Author went on to become not only a separate character, but a major recurring villain.

Web Original
""This was part of Silent Hill from the beginning. Konami wanted to make a full-3D survival horror game, but since they were making it on the PS 1 they had to wind back the draw distance to about six inches and make up a story about supernatural fog. Result: instantly iconic horror, and by following the same principle, Silent Hill 2 still looks fantastic despite the PlayStation 2's datedness.""
 * Zero Punctuation's Yahtzee declared that older horror games are more frightening than the newer ones, because the older games had to have "fog" due to technical limitations, and the monsters weren't as well fleshed out, leaving the details up to the viewer's imagination. And when it's up to your subconscious, it's always scarier.

""I think it was Stephen King who said that horror has to be cheap, because big budgets require big explanations. If a company is spending tens of millions of dollars on special effects, a filmmaker is compelled to show the entire monster in loving detail. That kills the mystery, and with it, the horror. It's actually better to cheap out, because then the filmmakers have to use darkness, and mystery to hide the fact that they're made of rubber and string, hence escalating the potential for horror.""
 * This was part of a column he wrote about several "rules" game developers should follow, one of which was something like "Thou Shalt Always Embrace One's Limitations", which is this trope in a nutshell.
 * He also thought that Driver San Francisco was all the better for explaining the body-jumping mechanic and all Acceptable Breaks From Reality as part of Tanner's Adventures in Coma Land. When a chase ends with the target escaping out of the gameworld's limit, the game hangs a lampshade on with Tanner having to make excuses for losing him without saying "He went past the edge of my dreamworld".
 * From The Furious D Show, a blog about pop culture and the business behind it, Hollywood Babble On & On #528: The Curse of the Dark Castle


 * A music editor decided to make the turrets from Portal sing. Some parts of the song didn't work out well, so the editor made a story about this crazy person who blew up Aperture Science Enrichment Center before he could finish. Watch it here!
 * The author of the Chaos Timeline originally had planned to call the internet of this world "Weltnetz" but found out that German neonazis use this term already for the existing internet, so he changed it to "Weltsystem".

Western Animation

 * Similar to the Pixar example above, Veggie Tales came into being because the creators were limited to armless, legless, hairless characters thanks to rudimentary CGI.
 * Beast Wars was an early All CGI Cartoon, which made it quite expensive. As a result it had a smaller cast than other Transformers shows, leading to a stronger focus on the characterization of the existing characters.