- Shuffling the locations of items and abilities required to advance the game
- Altering the level ordering or layout of the game world
- Changing locations and attributes of the enemies
- Changing the capabilities or stat growth of the player character
- Graphical changes such as swapping textures or using them in unexpected combinations
Randomizers can breathe fresh life into old games by taking something familiar and rearranging it to create new experiences that players haven't seen before, or opportunities that never existed in the vanilla game. They can also turn what was previously a linear experience into something more open, by allowing players to take alternative routes through the game that were previously not possible.
The core of a randomizer is the randomization algorithm, whose logic must be carefully cultivated to ensure that it does not produce unwinnable situations or undesirable gameplay.
Randomizers are especially popular among speedrunners, where they offer a unique challenge to players who are already familiar with the vanilla game. Speedrunning a randomized game requires players to push their abilities to another level - as well as the rote memorization and mastery of game mechanics ("execution") already required in a standard speedrun, they must also become proficient at routing unfamiliar paths or adapting their gameplan on the fly.
Naturally, speedrunners being what they are, they will also use or abuse knowledge of the randomizer algorithm itself to gain information or predict the future. Even if they don't know exactly what the randomizer will do, they know the kinds of things it could do, or may know what its limitations are.
Randomizers also allow for an interesting kind of race, in which all runners are given the same, never-before-seen randomized seed and tasked with discovering the most efficient way to complete the game. These races can attract dozens or even hundreds of players, and knowing one's opponent's tendencies and adapting to them can give rise to a robust Metagame.
A related development is "Bingo" mechanics, where the game itself is not randomized, but players are instead assigned a bingo card of random in-game objectives to complete, forcing them to approach the game in a different way than they usually would.
Compare the Roguelike genre, in which games are intentionally built around a randomization engine to provide gameplay variety and unexpected elements.
Examples With Their Own Pages
- A Link to the Past: Randomizer (includes the "SMZ3R" combination randomizer with Super Metroid)
- Final Fantasy IV: Free Enterprise
- Ocarina of Time: Randomizer
- PK Scramble!
- Zelda Randomizer
- Zelda 1 Randomizer
Examples Without Their Own Pages
- The Legend of Zelda: Link's Awakening: Link's Awakening DX Randomizer, or LAXDR, shuffles the locations of chest contents, seashells, golden leaves, heart pieces, and optionally, dungeon keys. This results in the trading sequence no longer being required to beat the game. There are a handful of other quality-of-life changes, such as removing long quest lines that would otherwise be required to open item locations.
- Doom mod Corruption Cards makes players choose from a randomly-chosen set of cards at the start of each level, each of which provides a game-altering effect. Cards can have simple effects (ex.: "All projectiles travel faster"), complicated ones ("One monster is cursed. It will cause a nuclear explosion when killed."), and some that can even cause Genre Shift ("No monsters, but a special Revenant stalks you.")
- Epic Battle Fantasy 5 has the Custom Game option "Random Equips", which shuffles the locations of equipment and makes all purchasable equipment (including festival-exclusive equipment) available from the start.
- Bug Fables has the Medal Randomizer mode, which is activated by naming your save file "MYSTERY?". In this mode, all medals are in random locations and they won't be revealed until you pick them up.
- Chrono Trigger:
- The "Eternal Nightmare" randomizer is fairly tame by randomizer standards. It shuffles character, equipment, enemy, and tech stats, shop inventory, and treasure locations, as well as player character color palettes. The game still follows a fairly linear path; in practice, the most impactful change is the chance to find endgame equipment much earlier, trivializing the game's difficulty.
- The "Jets of Time" randomizer, in the style of Final Fantasy 4: Free Enterprise, gives the player access to the Epoch at the beginning of the game, converting what is usually a rather linear game into an open-world scavenger hunt. Character pickups, loot, and enemy drops are shuffled by default, with several other modes being optional. Many aspects of the game are rebalanced to accommodate the randomized structure.
- Each entry in the Dark Souls trilogy and their predecessor Demon's Soulsnote have item and enemy randomizers. For added zaniness, the enemy randomizer can be set to allow regular enemies to be replaced by bosses, create Anti Climax Bosses by replacing them with Mooks, or replace every enemy with the final boss.
- Final Fantasy Franchise:
- Final Fantasy V:
- Ancient Cave - Inspired by the mode of the same name from Lufia II: Rise of the Sinistrals, the regular gameplay is gone, replaced with a roguelike dungeon crawl down 100 floors of increasing difficulty (and to prevent level grinding, the SNES version restricts the player by a timer on all non-boss floors, and boss floors have a limited number of encounters); items, equipment, jobs, and spells are all hidden in the chests strewn across these floors. Both the SNES version and the GBA rerelease have Ancient Cave mods; however, the latter is built on top of another mod that rebalances the jobs to make all of them more viable so keep that in mind when playing.
- Career Day - An open world randomizer that shuffles bosses between locations and the players goal becomes collecting the four tablets to open the way to the void to fight Neo-Exdeath.
- Grand Cross a randomizer made by the ever prolific abyssonym that allows ridiculous levels of customization.
- The GBA version has not one, but two randomizers, links collated here.
- Final Fantasy VI:
- The "Beyond Chaos" randomizer shuffles treasure locations, party and enemy stats, palettes, sprites, and seemingly almost everything else. As the name implies, it tends provide fairly chaotic results even by randomizer standards; the mod's author says that it's intended for casual play more than competitive racing.
- The "Worlds Collide" randomizer gives the player two random party members and the airship at the beginning of the game as well as the ability to swap freely between the World of Balance and the World of Ruin (something that's impossible without glitches in the vanilla game). Character, item, and Esper locations are randomized, and enemies are scaled to the party, meaning the game lends itself to a Low-Level Run. It is geared toward the competitive racing scene, and the mod's official Discord server has a dedicated racing section.
- Final Fantasy VIII has Maelstrom, which is compatible with both the classic release of the game, including the version found on steam, GOG etc., as well as the Remastered version. Some of the options, like randomized draw points, are currently only compatible with the old version, but the program is being developed constantly and features are being added and made compatible all the time.
- Final Fantasy Tactics has Rumble Chaos Crashdown, yet another abyssonym project, and like all of abyssonym's projects, features ridiculous customizability and special surprises.
- Final Fantasy V:
- Kingdom Hearts:
- Kingdom Hearts has a randomizer for the HD 1.5+2.5 Remix PC release. It randomizes weapon stats, item checks, Dalmatian locations, bosses, enemy drops, and so on. Win condition is to find all items needed to complete the two Destiny Islands days, which are scattered throughout the worlds of the game. On finding everything, you turn the items in to Kairi on both days and instead of the final night as in the original game, you proceed to the final boss gauntlet.
- Kingdom Hearts II:
- The original PS2 release has a randomizer for the Final Mix+ version which shuffles items in chests, cutscenes, and level-ups, just like other randomizers. The win condition is to find the three Proofs and then defeat Xemnas. However, it also shuffles the bosses, meaning that in low-level areas, nothing is stopping the runner from encountering a Data Organization XIII member. The randomizer is still in alpha, because shuffling bosses around can break the game, but this is slowly being fixed.
- The PC version has a randomizer for the HD 1.5+2.5 Remix that's bundled with the modding tools which has the same features as the above PS2 version, with the same win conditions.
- Kingdom Hearts: Birth by Sleep has a randomizer for the HD 1.5+2.5 Remix version, featuring the usual set of features like changed item pools and such. However, in addition to enemy randomization bosses can be included in a world's enemy pool replacing strong enemies, and vice versa.
- Kingdom Hearts III has a randomizer with the usual set of features as well as compatibility with certain mods. The clear conditions are to find three Proofs a la the Kingdom Hearts II randomizer and then proceed to the final boss fight.
- Pokémon has a wide variety of randomizers, including but not limited to: being able to randomize the Pokémon themselves, their types, movepools and abilities. The Trainers, levels and items can also be randomized. Funnily enough, this was one of the original concepts for the series itself, with each game procedurally generating various aspects of the world and Pokémon selection based on the player's Trainer ID number, before the much simpler One Game for the Price of Two setup was decided upon instead.
- Super Mario RPG has an open world randomizer where the goal is still to assemble the seven stars to repair Star Road, but the bosses that hold the stars are no longer where you expect to find them and your party can end up a little...different, to say the least.
- Axiom Verge received a randomizer as a third-party mod. Years after release, an official randomizer was added, giving options for vanilla progression, speedrun progression and low% progression.
- Bloodstained: Ritual of the Night got a built-in randomizer mode as free post-launch DLC, in lieu of the Roguelike mode originally offered in the Kickstarter campaign. While the castle's layout remains the same, shard drops (including progression shards) and item placement (including key items) are randomly shuffled between enemies and chests. Shuffled progression shards and key items may make you take a very different route through the castle to reach the end bosses.
- The remake of La-Mulana, and La-Mulana 2, each have randomizers, starting with the standard item shuffle and going to entrance, shop, and sometimes even boss randomization... as well as which weapon one starts with. Thankfully for quality of life, Lemeza or Lumisa can start with some of the items such as the grail, Mirai.exe, and TextTrax (useful for recording what's in each shop).
- Super Metroid has a randomizer that works as one would expect, shuffling the locations of the various items to be collected. It also includes options for the user to choose which glitch tricks (if any) can be taken into consideration with item placement.
- Metroid Fusion has one nearing a full release. Given the linear nature of vanilla Metroid Fusion there will always be the risk of soft-locking yourself if you're not careful. At the time of writing there's also still a reasonable chance to encounter unbeatable seeds but the only requirements to beat the game are to reach a point that Samus can open the Level 4 Security locks, defeat the SA-X, and set the station on a crash course with SR388 before escaping the BSL. The game tells you that you only need three particular items, but the reality is you require the Missiles, Morph Ball, Bombs, Charge Beam, Speed Booster, Plasma Beam, Gravity Suit, and either the Space Jump or Hi-Jump Boots so Samus can open the locks, escape the bowels of Sector 4, reach the control room on the Main Deck, and actually damage the SA-X. A unique standout feature is that the developer added the Ice Beam, normally available only in the last sixty or so seconds of the game, into the item pool with the full functionality expected of it from previous games in the series. The individual beams were also given their standalone behaviors from Super Metroid.
- In the unofficial 1.2 update to Another Metroid 2 Remake, completing the game in under four hours unlocks Random Game+ mode, which shuffles the locations of all the major upgrades (for example, you might get the High Jump Boots as early as the Golden Temple, but have to wait until the Tower to get the Charge Beam). The lava starts off at the level just below the Distribution Center, allowing you to explore everything up to that point in whatever order you want, though you have to defeat all the Metroids in those areas before you can go any further. Some minor modifications are made to the levels so you can't get trapped without a way to progress. There are also options that allow you to shuffle just the regular item expansions or to shuffle the item expansions with the major upgrades.
- Celeste has a mod that creates a randomized level from any room in the 9 chapters and all B and C sides. Before playing, the player can choose which chapters to pick levels from. Additionally, there are a few extra settings, including one that scatters gems around a randomly-generated labyrinth that the player has to navigate and collect.
- Celeste also has another mod that provides variants to spice the gameplay including flipping controls, setting the whole room underwater, and many more. A setting in this mod allows these to be randomized as well, with settings that disable or enable any of these variants to be included or excluded. And of course, this works with the level randomizer, so using both could guarantee chaos.
- Sonic Adventure 2 has a fanmade randomizer for the Steam version of the game that allows you to change several things:
- Every character begins with all upgrades, and the characters who can't normally get those upgrades (such as the Mystic Melody for the multiplayer characters and Eggman without his mecha) receive them to make life easier for you.
- Level orders are randomized, and are no longer tied to Hero or Dark Story. The missions you have to do are randomized too, so you may end up having to find lost Chao or collect 100 Rings in the main story.
- The characters you use, and the ones you fight against in player character battles, are completely different from the normal game, and include every multiplayer character, so you might end up playing through City Escape as Chaos Zero or Death Chamber as Eggman outside of his mecha (though every level will receive edits to make it easier if it's a level for a different type of character). There are also model swaps for the playable characters, such as 2020 film Sonic over Sonic, Gemerl over Metal Sonic, Shade over Tikal, and Wario over Knuckles, and a few characters, like Amy and Rouge, have alternate outfits. Omochao also has a new red and black palette.
- Kart models and stats are randomized.
- Cutscene order is also randomized, removing any semblance of the game's normal story in a funny way.
- Dialogue lines both during gameplay and cutscenes are swapped with other lines from this game (and, if enabled properly, lines from Adventure DX) because it's hilarious.
- Music is randomized both in cutscenes and gameplay, to amusing effect.
- The Binding of Isaac:
- The unlimited items mod, which has existed since modding the game was a thing but got most popular after the release of dedicated modding tools in Afterbirth+. It adds thousands of procedurally generated items to every pool. Definitely an interesting way to shake up your runs.
- Eden is a character added in Rebirth that lets you play a mild randomizer. They start with a random passive and active item as well as random stats, giving you a different experience every time you start a run with them. In order to prevent cheesing resets, playing as Eden requires an Eden Token, acquired from a late-game boss.
- Repentance takes it a step further with the item TMTRAINER. It replaces every item for the rest of the run with a "glitch" item that looks like a jumbled mess of various sprites, has a garbled string of characters for a name, and assigns several random effects to random triggers. Things can get pretty broken. Or just kill you instantly. It's all random. The appropriately-named DELETE THIS challenge has you starting with TMTRAINER. Also, beating one of the final bosses as Tainted Eden unlocks "Corrupted Data", which permanently adds a small chance to generate glitch items even without TMTRAINER.
- Patch 1.5 of Stardew Valley added Advanced Game Options to, among other things, randomize the requests in the Community Center bundles, which are the primary measure of progress in the game.
- Hitman 2: A relatively simple mod randomizes Agent 47's starting inventory, with each item bound by its category (e.g. pistols can only be replaced by other pistols, explosives by other explosives, etc.). Item locations within levels are also randomized, as are guard inventories, with chaotic results. Guards are far more lethal to Agent 47— there are a lot more guns that will effectively OHKO him than those that won't— and even to themselves (the AI is pretty bad at handling explosives safely).
- Civilization 6 released a "Tech and Civic Shuffle" game mode in August 2020, which randomizes the Tech Tree and Civic Tree when enabled. Techs and civics within each game Era are shuffled, the tree layouts are changed, and unknown techs and civics are hidden.
- Fire Emblem: Some of the best known mods completely randomize the class, stats, growth rates, items, and join time of units. Many early randomizers use the GBA games as they are very simple to program but later randomizers also exist for much more complex games like Fates and Three Houses. Due to randomizers affecting units but not affecting voice acting, it often leads to humorous scenes like characters having voices that don't suit them like Mercedes with Death Knight's voice.
- FTL: Faster Than Light: While the game itself is already highly randomized, the final boss is always the same, funneling the player into one of a handful of optimal builds in any given run. With the Flagship Randomizer mod, the Rebel Flagship's layout and capabilities are randomized. The player is given a broad overview of the randomized design at the beginning of each run, encouraging them to build their ship to counter it if possible.
- XCOM: Enemy Unknown: The free "Second Wave" DLC gives the option to randomize several elements that are static in the base game, such as weapon damage values, funding levels provided by Council nations, and soldier statistics. The Training Roulette option randomizes most class abilities, allowing for combinations not possible in the base game.
- The Nintendo 64 port of Resident Evil 2 featured an unlockable Randomizer option, albeit limited to just randomizing item placements. Nonetheless it sure was ahead of its time, as years later randomizer mods for most games in the series sprung up. This included Resident Evil 2 itself (for its 2006 Sourcenext PC port). A randomizer for the Claire A/Leon B route allows players to not just randomize items, but enemy placements, which means as early as the first screen of the game you could have an army of Mr. X Tyrants coming at you. Voice lines can also be randomized, solely for fun.
- Fallout: New Vegas: The NVRNG mod randomizes many aspects of the game, including starting SPECIAL attributes, container contents and enemy loot, character models and sizes, weather, and jump height. The power curve is nonexistent, and the already somewhat wacky atmosphere of the game is magnified to ludicrous extremes when you find yourself facing a three foot tall Powder Ganger armed with a goddamn Fat Man.
- Ultima IV: The Ultima IV Map Randomizer changes the layout of Britannia, while updating the dialog of people who tell you specific sextant coordinates for things. While we're at it, it also allows for options like diagonal attacks and a few bugfixes.