If you meant a — there was also a 2004 mobile game and a 2012 Facebook game — but the famous "3 key code" story is purely from the SereneScreen PC screensaver era.
That's the — more legend than fact, but rooted in a real easter egg. marine aquarium 3 key code
With all three keys in hand, the adventurers approached the entrance to the Golden Reef. They inserted the keys into a ancient lock, and with a satisfying click, the entrance opened. The group swam inside and discovered the breathtaking Golden Reef, teeming with life and filled with treasures. If you meant a — there was also
No "3" key was involved. But the number "3" likely came from of the screensaver, or confusion with another screensaver (e.g., "After Dark" or "3D Fish"). They inserted the keys into a ancient lock,