Adventure was the 1980 Atari 2600 game containing Warren Robinett’s hidden room, often called the first major video-game Easter egg.
Robinett designed the game as a console adaptation of the text adventure Colossal Cave Adventure. Players explored a graphical kingdom, searched for objects, and used colored keys and items to reach a goal involving the Golden Chalice.
Robinett hid a secret room that could be reached by carrying a nearly invisible gray pixel into a specific area. Entering it revealed his name, allowing players to see the designer’s credit inside the game despite Atari’s policy of not crediting programmers publicly.
The term “Easter egg” was applied later to hidden features in software and games. Adventure is frequently described as the first known video-game Easter egg, although the exact wording can vary depending on whether minor earlier secrets are counted.