Rogue

Two students who played D&D and had been struck by Colossal Cave Adventure built a maze that changed shape every time you played. About its famous permadeath (die and you start over), this map first wrote that it was a case of a technical constraint turning into meaning — that turns out to be wrong. A save function did exist. But players began reloading their saves to keep only the best outcomes, which broke the design's tension of a single, unrepeatable attempt. So the developers deliberately added code to delete the loaded save. In later years, Wichman, one of the creators, said he disliked the word permadeath itself and preferred to call it consequence persistence — the same rule as not being able to take back a move in chess. In 2008, an international conference in Berlin defined the genre with a list of nine defining traits and six additional common ones, fifteen in all (drawn inductively from a canon including Rogue, NetHack, and Angband, with the caveat that lacking a trait doesn't necessarily disqualify a game as a roguelike) — a rare case where a genre's definition was settled at a conference.