Modern Warfare 2 has a level ("Contingency") with a setpiece that can't be seen during normal gameplay — as you fight off enemy forces, Price goes inside the Russian submarine and activates a nuclear missile. It was originally possible to follow Price inside the sub yourself (instead of being stuck outside on the dock), and could watch as he went through the process of arming and firing the missile in real-time. Come Modern Warfare 3, the first level of the game concludes with a sequence where you follow your AI partner inside a similar Russian submarine to disable it, using the same animations and level layout as the scrapped sub interior from the previous game.
Modern Warfare 2 also had a planned (but scrapped early on) sequence where Russian forces would invade the International Space Station (ISS), forcing the onboard staff members to defend the station and prevent it from being hacked. This was stripped down in the final game to an interactive cutscene where an astronaut watches the nuclear device detonate before being hit by a shockwave. Call of Duty: Ghosts reuses the level idea for the first stage, where a pair of scientists defend the ODIN space station from enemy forces before it disintegrates and the player character(s) accept their fate.
More like "Refitted For Another Franchise," but the beta for Danganronpa, originally called DISTRUST, had a trust mechanic that decided the fates of certain characters. This would later be reused for Virtue's Last Reward, the second game in the Zero Escape series, also by Spike Chunsoft.
An early version of Doom II's Map 10 can be found in an alpha version of the first game.
The footage leaked from the original version of Doom 4 showed human soldiers preparing to fight off a demonic invasion on Earth, meant as both a supposed sequel to the events of Doom 3 and a remake of Doom II. While the game ended up turning into the rather different DOOM (2016), the "Hell on Earth" concept was reused for its sequel Doom Eternal.
Dragon Age II was supposed to receive an Expansion Pack, titled The Exalted March, which would concern the eponymous holy crusade against Kirkwall and Hawke's efforts to repel it. Due to DA2 cold reception, the plans for the expansion were aborted, but Word of God is that most of its storyline was incorporated into Dragon Age: Inquisition, the third core installment, in one way or another.
Fallout: Van Buren was canceled, but the majority of the plot and Caesar's Legion was incorporated into New Vegas. And the parts of Van Buren that weren't part of New Vegas proper were used for DLC, namely Honest Hearts.
The design for the Bonus Boss, Morpho Knight, is based on a piece of concept art for the cancelled GameCube Kirby game. The artbook in which the design previously appeared labeled it as "Meta Knight", though it's unclear what the design was truly for.
The concept of a final boss with heavy connections to Dark Matter was initially intended for Kirby: Planet Robobot. Concept art reveals that Star Dream, rather than linking with the Access Ark which would reveal itself as a machine similar to Galactic Nova, would have revealed itself to be a robot modeled after Zero Two. Star Allies reworks the idea of a destructive boss linked to Zero and Dark Matter into Void Termina. Concept art (presumably for the Soul fight) even shows Kirby in an area baring a similarity to Void Termina's innards.
The Horse Call in Twilight Princess dates back to this game. It was originally a Reed Whistle but was scrapped in favor of Epona's Song. Another planned mechanic with Epona for the 1998 game was being able to use swordplay while riding her, which was added in Twilight Princess as well.
The game was originally planned to have an Ice Temple and a Wind Temple, hence why two of the Medallion icons are modeled after ice and wind respectively (it also explains why the Forest and Water routes in Ganon's Tower are themed around wind and ice, again respectively). They were replaced with the Forest Temple and the Water Temple, which ended up relegating the Ice Cavern to a Mini-Dungeon. The Wind Waker eventually introduced the Wind Temple, while the posthumous former sage of that dungeon, Fado, is named after the character who was going to be the sage of the scrapped Ocarina version before Saria took the role for the repurposed version. Ice-themed dungeons went on to appear in subsequent games, including an Ice Temple by name in Phantom Hourglass.
The Hero's Shade teaching you moves in Twilight Princess is similar to an unused concept for Majora's Mask where Link learned skills via cutscenes.
Word of God is that this is the case for the two additional dungeons that didn't make the cut due to time constraints, which is why the HD remake didn't incorporate them.
The E3 announcement trailer for the game shows that Link originally had a sneaking ability for stealth portions of the game. It was replaced with hiding inside barrels. Years later, Breath of the Wild implemented a stealth ability.
Dummied Out code for Twilight Princess indicates that there was supposed to be a regular Shield Surf mechanic rather than the more limited snowboarding on Snowpeak in the final version. Shield surfing ended up being featured in Breath of the Wild, and you could do it anywhere from the moment you found your first shield.
Breath of the Wild had more DLC conceptualized than what was officially released in the Expansion Pass. However, as the number of DLC ideas and the size of the content were substantial, the development team decided these ideas would serve better as building blocks of a direct sequel.
2 also has an unused concept for an NPC companion called "Sparky the Dog", which would have resided on the Normandy and been referred to as a loyal friend for Shepard. This was later reused for the "KEI-9" robot dog companion, which was included as part of the Collector's Edition.
Artbooks showed early ideas for Hunters to be able to use various bugs to assist and fight monsters. This was finally implemented in the fourth generation as the Insect Glaive.
The artbooks also feature concept art of an unused "Crypt Hydra", a two-headed mummy snake creature, hailing from before it was decided that the series would go for a Low Fantasy setting. The two-headed serpent concept was eventually reused in Monster Hunter Generations with Nakarkos, with the hydra heads serving as disguised tentacles for the giant cuttlefish-dragon.
Some artwork from Generations shows a scrapped gunner weapon taking the form of a "Hunting Hound", a customizable canine companion which the player would guide into battle. The idea was later revisited in Monster Hunter: Rise with the Palamute companions.
The original concept for Rise Kujikawa was a blonde, chain-wielding ice queen delinquent who was a fully-controllable party member. By the time of the final game, Rise's blonde hair was lost when she was redesigned to look more like her voice actress (some aspects of the original design went to Social Link NPC Ai Ebihara), the delinquency aspect was dropped to avoid redundancy with fellow party member Kanji Tatsumi, and she was moved to a Mission Control role providing support for the party. In the next game, party member Ann Takamaki uses a number of these rejected concepts: delinquency, blonde hair, and a frontline Action Girl who fights with whips.
Originally, the Killer was going to have been either Yosuke or Yukiko, but their intended motives were considered too generic. The concept of a party member being one of the antagonists was later used for Persona 5.
Concept art had the Killer, Adachi, wearing a yellow raincoat. Persona 4: Arena Ultimax has him wear one during his intro.
Dummied Out battle data in Red and Blue showed that there was once going to be a Bonus Boss fight against Professor Oak, who would use the starter not chosen by you or your rival. This came back in Pokémon Sun and Moon for the Final Boss fight against Professor Kukui, who pulls the same stunt.
Word of God says most of the new Pokémon introduced in Pokémon Gold and Silver were originally planned to be in Red and Blue before being cut for space. Subverted with the Kotora family, however, since they were cut from Red and Blue, added into the Spaceworld prototype of Gold and Silver, and then cut again.
The Pokémon Gold and Silver Spaceworld demo featured many scrapped Pokémon that would eventually be repurposed later on in the series: Evolutions for Lickitung and Tangela, a pre-evolution for Mr. Mime, and a grass-type Eevee evolution were cut from Gold and Silver, then made a reality once Pokémon Diamond and Pearl was released several years later. Another scrapped evolution from the Spaceworld demo was an evolution for Farfetch'd; decades later, Farfetch'd would finally gain an evolution in the form of Sirfetch'd in Pokémon Sword and Shield. And an unused turtle Pokemon◊ from the demo resembles Tirtouga, which was first introduced in Pokémon Black and White.
Pokémon Gold and Silver were originally going to contain a skateboard in addition to the bicycle; an idea that ultimately never made it into the final game. Years later in Pokémon X and Y, the player character is given roller skates in addition to getting the bike later on.
The music for the Clefairy dance on Mt. Moon in Gold & Silver is recycled from an early draft for the Trainer victory theme in Generation I. Interestingly, it's also used as the battle victory theme in Pokémon Stadium 2.
Snowboarders are a cut Trainer class from Generation III that were reused for Generation IV.
The side-mission "The Smell of the Grease Paint" from Red Dead Redemption 2 is a tweaked version of one cut from the first game that was found by modders in the files of the PC version. Arthur has to help a woman in a traveling show with her giant and dwarf castmates. The original version in I was to find lonely a lonely giant and lonely dwarf and try to get them to be friends.
Earlier builds of Serious Sam: The First Encounter featured a Death Ray weapon called the "Ghostbuster" that was scrapped due to issues with the model. The weapon was reimplemented in the Serious Sam Classics: Revolution port and the "Death Ray" add-on to the Lasergun in Serious Sam 4 functions similarly to it.
Shigeru Miyamoto once stated he had wanted to have Mario ride a dinosaur as early as Super Mario Bros.. However, the NES limitations prevented it from happening (they got closer to the concept in Super Mario Bros. 3 with Goomba's Shoe, which is functionally similar to Yoshi). It was deemed impossible until the fourth main game, Super Mario World for the SNES.
Originally, Super Mario Galaxy was going to feature more levels, characters, enemies, and power ups (such as the Cloud Flower and the Rock Mushroom, as well as the inclusion of Yoshi), but all of them were dropped from the final version of the game. They were planned to be implemented in an expansion pack called Super Mario Galaxy More, but the development team decided that they had more than enough ideas to justify making a full-fledged sequel instead, which became Super Mario Galaxy 2.
One of the prototype character designs for Sonic was a rabbit who would be able to grab and throw objects and enemies with his long prehensile ears. The idea was scrapped in favor of a hedgehog that could roll into a ball, and while throwing objects never became a mainstay of Sonic's gameplay, Sonic Adventure 2 included an unlockable upgrade called "Magic Hands" that allows Sonic to turn enemies into throwable objects, and the night stages in Sonic Unleashed involve a lot of grabbing as well. Sonic Team also went on to create another game based on the concept of grabbing and throwing, Ristar, and one of the enemies in that game is a rabbit which attacks using its ears.
Another prototype character design was an armadillo, which proved popular among staff members alongside the hedgehog concept. While the hedgehog won out in the end and became Sonic, the armadillo concept was revisited and became Mighty in SegaSonic the Hedgehog, who went on to become a recurring side character in the franchise.
Vector was originally supposed to be part of a rock band with Sonic in the first game, which was going to be seen on a sound test screen which showed them playing whatever music was selected. The concept was scrapped when that screen had to be cut out due to memory limitations. He was reintroduced in Knuckles Chaotix, and became a recurring character; although the idea of him and Sonic being in a band has since been mostly dropped, as have the other band members, Sonic himself was in a band with his siblings in the animated series Sonic Undergroundnote and prior to that screen being dropped, he was in a band in Sonic the Hedgehog Story Comic, and Vector plays music (badly) with his teammates in Sonic Heroes.
The first game was originally going to contain a rabbit enemy named Splats, which was scrapped so late in development that it managed to receive official merchandise. Decades later, Splats appeared in Sonic Mania, both as an enemy and broken down in piles of trash.
Time-traveling was a concept first conceived for Sonic the Hedgehog 2 but wasn't added into a game until Sonic CD. Dust Hill, a crumbling, worn-down variation of Green Hill set in a "bad present" where Dr. Robotnik has succeeded in taking over the world (the name of which was often attributed to a desert level seen in pre-release screenshots), may have been revived as Sonic Forces' decidedly arid take on Green Hill.
The canceled arcade Puzzle GameSegaSonic Bros. contains music which was later repurposed for the "Get Blue Spheres" special stage in Sonic 3 & Knuckles, which also uses similar gameplay mechanics. The same game depicted Sonic as being a triplet, a concept which also appeared in the early cartoon Sonic Underground. The concept of an arcade game with previously-unseen red and yellow counterparts for Sonic appearing alongside him (and the trio being crammed into the title screen's logo) was also used for SegaSonic the Hedgehog. SegaSonic Bros. itself subverts this by containing within its data, but not actually using, sprites of the band members who were originally intended to appear on Sonic 1's scrapped sound test screen.
Sonic & Knuckles is another unusual example. It consists almost entirely of material that was originally intended for Sonic the Hedgehog 3; partway through development, Sonic 3 had to be split in half due to time and cartridge space constraints, and Sonic & Knuckles is essentially the second half of that game. The two games can however be locked onto each other to create Sonic 3 & Knuckles, which is the official full game (with only minimal differences from how it would have been had it not been split in half), and is the longest in the original Sonic trilogy.
In a rather unique and bizarre example, Sonic Crackers was a prototype game which featured Sonic and Tails tethered together by rings that were connected via an energy beam. Although it appears to have primarily been an engine test and many elements of it were dropped completely, up to and including the title and main characters, it was revisited and heavily reworked (retaining only the music and "duo connected by special rings" mechanic), becoming Knuckles Chaotix.
Sonic Adventure: The music used for the "Pleasure Castle" section of Twinkle Park was first meant to be used in Sonic 3D Blast. The original intent for said game was for the Special Stage music to change depending on whether you accessed it through Tails or Knuckles; unfortunately, Knuckles's Special Stage theme was cut due to cartridge space limitations, and Tails's theme was used for both varieties.
Uru: Ages Beyond Myst is an interesting example. The game was intended to be significantly more ambitious than the finished product ended up being, with regular online content updates continuing the story and extra Ages to explore. When the online component was cancelled, some of said content was reused into a pair of expansion packs. When the online was Uncancelled, several plot threads were picked up for a bit before the online was dropped again and the plot was Left Hanging. Everything was eventually finished in Myst V: End of Ages, and one scrapped Age was recycled for the later Spiritual Successor, Obduction.
The levels Witchyworld, Glitter Gulch Mine and the lava side of Hailfire Peaks in Banjo Tooie were originally intended for Banjo-Kazooie. And in a case of Refitted For Spiritual Successor, the scrapped level Fungus Forest made its way into Donkey Kong 64 as Fungi Forest.
Kingdom Hearts was originally going to have Disney Castle and Pride Lands as playable worlds. Playable Disney Castle did appear in a beta trailer, but the programmers couldn't figure out the mechanics of playing as non-anthropomorphic animals in Pride Lands. They were later used in Kingdom Hearts II.
The Final World in Kingdom Hearts III was originally planned for the first game for when Sora sacrificed himself to free Kairi's heart. The result of his sacrifice was changed to him becoming a Heartless instead.
Final Fantasy II had a dungeon theme composed for it that, for whatever reason, ultimately went unused. It was later fleshed out, rearranged, and worked into Final Fantasy VI as "The Magic House".
When the whole dev team was working together to come up with Jobs for Final Fantasy V, Tetsuya Nomura came up with two - a new variant of the Ninja that had a Canine Companion, and a Gambler who used slot-machine-based magic and dice-roll-based damage. Neither made it into V due to time constraints, but Nomura was given creative control over two party members in Final Fantasy VI who have these Jobs - Shadow, and Setzer.
During the planning stages of Final Fantasy VII, the writers considered killing Barret Wallace but ultimately decided against it because they didn't think it would have enough of an impact. In Final Fantasy VII Remake, Sepiroth stabs Barret through the chest in order to draw out the Whispers; he would have died had they not intervened.
At the end of The Secret of Monkey Island, Guybrush was originally supposed to follow LeChuck into an alley and down into an underground passage. The underground passage was brought back in Monkey Island 2: LeChuck's Revenge, and if Guybrush takes the elevator up he can go to the alley from the first game, only with a barrier blocking the way to the street. A remnant of this in the first game is the way that LeChuck (disguised as Fester Shinetop), calls you into the alley - entirely optional, but if you do it, you would automatically expect to go there later in the game as the door is locked at that point.
Ditto from the Pokémon series was meant to be among the Poké Ball summons introduced in Super Smash Bros. Melee, with the idea being that it would take the form of the player who activated it and function as a temporary AI teammate. The GameCube couldn't pull this off without crashing, however, so the concept was shelved until Super Smash Bros. Ultimate over 15 years later.
Bowser, King Dedede, and Mewtwo were planned to be in the first game; they did not get in due to time and budget constraints. Bowser and Mewtwo would eventually make it into Melee, while King Dedede would not join until Brawl.
Final Smashes were intended to be included as early as the original Nintendo 64 game, but the console couldn't handle how the developers wished to implement them, so they weren't added in until Brawl on the Wii.
Pit was also considered for Melee as a retro character (among many other characters), but the Ice Climbers were added over him due to their gameplay potential. Pit would go on to join in Brawl with an updated appearance, which would inspire Sakurai to create a new game in the series.
Hideo Kojima had given Masahiro Sakurai his blessing to add Solid Snake to the series as soon as Melee, but was not able to include him in the roster due to development being nearly complete at the time. He would instead make his debut in Brawl.
Likewise, the Villager was considered to join the battle in Brawl, but Sakurai couldn't think of how to implement them due to how peaceful a game series Animal Crossing was. He ended up figuring it out when it came time to plan the base roster for 3DS and Wii U.
Shigeru Miyamoto personally requested Pac-Man be made a playable character for Brawl, as Pac-Man is his favorite video game character, but — like the previous two examples — Sakurai was unable to think of a good moveset at the time. He would make his debut in 3DS and Wii U, which happened to be the first Smash game developed by Bandai Namco, which owns the character.
A section of Chapter 5 of King's Quest (2015) consists of some ideas that were developed for earlier chapters (according to some concept art) but cut, among them a goblin riding on a rat and an entire song by Whisper. They surface here when old Graham becomes confused about the earlier stories he had told his granddaughter Gwendolyn, with her correcting him on the details as a meta-commentary (she literally says that the Whisper song, in particular, would've "made that chapter too long.")
Undertale was originally going to have a magic system, but as the lore developed and humans were firmly established as non-magical, it had to be cut. Deltarune has you play as a party of three, and the two non-humans do have access to magic.
The concept where Maria Tachibana joined the Flower Division as its latest recruit from America following the Great Kanto Earthquake in Sakura Wars (1996) would later be reused in Sakura Wars: The Movie, with Ratchet Altair taking Maria's place.
Sakura Wars 4: Fall in Love, Maidens was originally going to have Ichiro Ogami travel to New York City and Taiwan to lead the new combat revues that were based there. However, the plans were soon scrapped because the Useful Notes/Dreamcast was ending production and Overworks was given only ten months to finish the game. The New York setting was eventually used for Sakura Wars: So Long, My Love.
Shanghai was one of the original Combat Revue candidates for the 1996 game, but it was scrapped before development began. It would eventually be included in Sakura Wars (2019).
Tekken was intended to have Devil Kazuya with wings (as seen in concept art), P. Jack with the ability to fly (he has a jetpack in the game though it is not functional), and Kunimitsu as a female character (she ended up using Yoshimitsu's male assets due to space limitations). In addition, the boss characters would have differed more substantially than being Moveset Clones with a couple of extra moves. These were all implemented in Tekken 2, as the hardware was now up to the standard to include them.
Spyro: Enter the Dragonfly was supposed to introduce a pink female dragon named "Ember". Due to developmental change, there wasn't anywhere in the game for her. She was scrapped but reused in Spyro: A Hero's Tail, where Ember shortly appeared for two scenes in the game (and can be played using a skin).
The original Darius was planned to feature 26 bosses, one for each level, but this was not possible for the final release due to time and space limitations. Some of the scrapped bosses (Driosawm, Hyper Sting and Little Stripes) would be featured in Darius II instead and the original 26 bosses plan was restored for the game's Super Darius port, 3 years after the release of the arcade version.