http://www.jimmys-adventures.net/adventure-atari-easter-egg/
Where is the secret room in Atari’s Adventure with the creators names? (Easter egg)?
Adventure – Atari Adventure Easter Egg – the First Known Egg!
1. Get the bridge
2. Take it inside the black castle
3. Find the central room that causes the screen to flicker even when there are no objects in it
4. Use the bridge to get into the secret chamber in the middle of that room
5. Inside that the secret chamber there is a “dot” — pick it up
6. Take the dot to the main hall way (below the golden castle)
7. Once here the dot will cause one of the hallway barriers to dissappear
8. You can then enter a hidden chamber that list a message from the programmers
9. (This game is from the 1985 era but it still contains an Easter egg)
10. There is also a secret room in the white castle that requires the use of the bridge
Adventure (atari 2600) Easter Egg