Akalabeth: World of Doom (/əˈkæləbɛθ/) is a role-playing video game created in 1979 for the Apple II by Richard Garriott, and published by California Pacific Computer Company in 1980. Garriott designed the game as a hobbyist project, which is now recognized as one of the earliest known examples of a role-playing video game and as a predecessor of the Ultima series of games that started Garriott's career. Garriott is the sole author of the game, with the exception of title artwork by Keith Zabalaoui.

The game attempts to bring the gameplay of pen-and-paper role-playing games to the computer platform. The player receives quests from Lord British (Garriott's alter-ego and nickname since high school) to kill a succession of ten increasingly difficult monsters.

The majority of gameplay takes place in an underground dungeon, but there was also a simple above-ground world map and text descriptions to fill out the rest of the adventure. The player could visit the Adventure Shop to purchase food, weapons, a shield and a magic amulet; the player's statistics can also be viewed here.

The game used concepts that would later become standard in the Ultima series, including:

The game was made by teenager Richard Garriott in Applesoft BASIC for the Apple II while he was attending high school in the Houston, Texas suburbs. Begun first as a school project during his junior year using the school's mainframe system DEC PDP-11, the game continually evolved over two years under the working title DND with the help of his friends and regular Dungeons & Dragons partners who acted as play-testers. Final development of the game began soon after his initial encounter with Apple computers in the summer of 1979, on an Apple II bought for him by his father and, later, on an Apple II Plus, but Garriott did not expect that the public would see his work.

Early versions of the game used an overhead view with ASCII characters representing items and monsters. However, after playing Escape, an early maze game for the Apple II, he instead decided to switch to a wire-frame, first-person view for the underground dungeon portions of the game, making it the first computer role-playing game with such graphics. The game asks the player to provide a "lucky number", which it uses as a random seed to procedurally generate the rest of the game, including dungeons and player stats; by using the same number the player can always return to a given world. The Ultima Collection version added savegame support while still using a similar random seed.

When the game reached version DND28B later that year (where "28B" refers to the revision), he demoed the game – now renamed to Akalabeth – for his boss, John Prosper Mayer, at a Webster-area ComputerLand, who suggested he sell the game in the store. Garriott consented and spent $200 to package and sell the game for $20 inside Ziploc bags, with photocopied instructions and a cover drawn by his mother. It warned "BEWARE FOOLISH MORTAL, YOU TRESPASS IN AKALABETH, WORLD OF DOOM!!", and claimed to offer "10 different Hi-Res Monsters combined with perfect perspective and infinite dungeon levels". California Pacific Computer Company received a copy, and contacted Garriott to publish the game. Garriott flew to California with his parents and agreed to receive $5 for each copy sold. The retail price of the California Pacific version, with cover artwork by Denis Loubet, was $35; Garriott claims that the game sold 30,000 copies, with him receiving $150,000, and that Akalabeth had the best return on investment, with later games "all downhill from there". The company suggested that for marketing purposes "Lord British" be credited as the author, and organized a contest for Softalk readers to figure out his true identity.

In creating Akalabeth, Garriott was primarily inspired by Dungeons & Dragons, for which he held weekly sessions in his parents' house while in high school, and the works of J. R. R. Tolkien, which he received from an in-law of his brother. The name derives from Tolkien's Akallabêth, part of The Silmarillion, though the game is not based on Tolkien's story. In the original game, the last monster on the need-to-kill list is called "Balrog", like the demonic monster from The Lord of the Rings, and unlike the later name for the monster in the Ultima games, Balron.