Adventure

Adventure is a 1980 video game for the Atari 2600 console where players control a square avatar searching an open world for a magical chalice, avoiding dragons and a bat that steals items. The game was created by Atari employee Warren Robinett, who left the company soon after submitting the source code, making it one of the earliest games to include an Easter egg: Robinett's name hidden in the game's code.