A randomizer is a Game Mod, ROM hack, DLC, or mode that inserts a random element into a gameplay system that had previously been static. Commonly, a randomizer takes the locations of items and abilities required to advance the game and shuffles them, rendering what had been a mostly linear experience more open. An algorithm or "logic" often governs item placement to ensure that the randomizer will not result in an unwinnable game. Some randomizers also alter the layout of the game world, the locations and attributes of the enemies, the capabilities and/or stat growth of the player character(s), and more.
Randomizers are popular among speedrunners. In addition to the rote memorization and mastery of game mechanics ("execution") already required in a standard speedrun, speedrunning a randomized game requires efficiently checking item locations and changing one's path through the game on the fly depending on the items found ("routing"), and knowing the item placement algorithm to predict where progression items are likely to be ("reading the logic"). Randomizer speedrun races in which all runners are given the same randomized seed and tasked with discovering the most efficient way to complete the game 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.
Examples With Their Own Pages
- A Link To The Past: Randomizer (includes the "SMZ3R" combination randomizer with Super Metroid)
- Ocarina of Time: Randomizer
- Zelda 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.
- 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.
- Final Fantasy Franchise:
- Final Fantasy IV: The "Free Enterprise" mod converts the otherwise quite linear Final Fantasy IV into an open-world scavenger hunt. The player is given two random party members and the Enterprise airship for free at the beginning of the game (hence the title), and quests can be completed in any order.
- 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.
- Kingdom Hearts II 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.
- 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.
- 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).
- 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.
- 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.
- 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.