NetHack is a single player dungeon exploration game that runs on a
wide variety of computer systems, with a variety of graphical and text
interfaces all using the same game engine.

Unlike many other Dungeons & Dragons-inspired games, the emphasis in
NetHack is on discovering the detail of the dungeon and not simply
killing everything in sight - in fact, killing everything in sight is
a good way to die quickly.

Each game presents a different landscape - the random number generator
provides an essentially unlimited number of variations of the dungeon
and its denizens to be discovered by the player in one of a number of
characters: you can pick your race, your role, and your gender.