Adj: Of a computer game sharing certain characteristics similar to the original game Rogue. Especially involving a single character in a large dungeon/tower, with a key focus on inventory management and stat-building. Generally free and open-source, with primarily ASCII graphics.
Notables: Angband, Moria, Nethack, ADOM, Omega.
PQ (Progress Quest) is a parody roguelike.
Angband is the best roguelike!