Nethack is the most celebrated member of the ancient and honorable family of games descended from Rogue and hence known as “roguelike”: bare-bones ASCII-graphics adventures set in randomly generated dungeons, in which the player fights monsters and collects items until he or she croaks.
Originally released in 1987, Nethack remained in active development as an open source project at least up until 2003, when the last major update was published. This long gestation period has made Nethack an extraordinarily rich, complex little universe, and endowed it with a mordant, anarchical sense of humor.
The character classes alone give you a sense of the game’s depth: you can play as an archeologist, a barbarian, a caveman, a knight, a samurai, a valkyrie, a tourist, or half a dozen other options. Nethack is a demanding game — its difficulty and quirkiness have kept it a cult phenomenon — but it’s more compelling than most of the chip-melting, big-budget graphical RPGs being released now.