NetHack is an open source single-player roguelike video game, first released in 1987 and maintained by the NetHack DevTeam. The game is a fork of the 1982 game Hack, itself inspired by the 1980 game Rogue. The player takes the role of one of several pre-defined character classes to descend through multiple dungeon floors, fighting monsters and collecting treasure, to recover the "Amulet of Yendor" at the lowest floor and then escape.

Roguelike is a style of role-playing game traditionally characterized by a dungeon crawl through procedurally generated levels, turn-based gameplay, grid-based movement, and permanent death of the player character. Most roguelikes are based on a high fantasy narrative, reflecting their influence from tabletop role-playing games such as Dungeons & Dragons.