Released on Christmas in 1979, Atari’s Adventure is considered the first action-adventure game. It also introduced the Easter egg to the gaming world. Move a dot down a corridor and your character–really just a colored square–will be able to enter a room, in which you see the words, “Created by Warren Robinett.” Back then, video-game developers weren’t given credit, so Robinett inserted his byline into the game. The Easter egg ate up five percent of the cartridge’s storage space, but instead of doling out the tens of thousands of dollars necessary to produce an Easter Egg-free version, Atari just left it in. Thus, the Easter Egg was born.