A roguelike is a game modelled on Rogue from 1980, traditionally featuring procedurally generated levels, turn based movement, and permadeath that ends the run on death. The 2008 Berlin Interpretation lists the traits used to judge how close a game sits to that model.
Rogue presented its dungeon as text characters on a screen, generated a new layout each time, and deleted your progress when you died. The games that copied it, including NetHack, Angband, and ADOM, kept those rules for decades in a dedicated community. At the International Roguelike Development Conference in Berlin in 2008, developers and players wrote the Berlin Interpretation, a scored list of high value and low value factors drawn from five canonical games, to describe degrees of likeness rather than a hard border.
Its high value factors include random environments, permanent death, turn based play, grid based movement, complexity from interacting systems, and resource management under scarcity. No single factor is mandatory under the Interpretation, which is itself the point: a game can miss several and still be meaningfully roguelike.
Modern usage is looser than the Interpretation. Many players now apply roguelike to any run based game with procedural generation and permadeath, including real time and action games. Traditionalists reserve the word for the stricter form and call the looser games roguelites, a split that explains most arguments about the label today.
In play"NetHack is a roguelike in the strict sense, with a new dungeon and permanent death on every run."