The Atari 400 version of Donkey Kong hid programmer Landon M. Dyer's initials for 26 years, requiring a specific sequence of deaths and difficulty settings to reveal. In Doom, the final boss's voice subtly reveals a message from creator John Romero, saying, 'To win this game, you must kill me, John Romero,' which many players missed. Nine years after its release, a 'CDPR Needs You!' recruitment poster was found hidden under Novigrad in The Witcher 3, speculated to be an artist's joke or a recruitment tool.