Nethack is a dungeon crawl game that includes yourcharacter, his faithful pet companion, some monsters and various other objects represented by a number of different text characters.You can choose from a wide variety of different character archetypes,
Industrial MUD is a free Multiple User Dungeon Telnet Server that is written from scratch. It is developed for Linux and includes a small internal programming language called Weld. Weld allows for artificially intelligent autonomous computer robot play
This is the Linux version of the classic 3D game of Doom. This software runs under either Xfree86 or SVGAlib. In case you don't know what Doom is, the object of the game is to kill as much as possible while finding your way through a maze.