Fathom

Release the mermaid on level two, but swim up and leave before her cage fully opens. Transform into a seagull and fly to the left or right to a volcano. The initials of each programmer (Rob Fulop, Michael Becker and Wilfredo Aguilar) will replace the volcano fireballs.

The manual mentions to watch for a 'special surprise' for completing the game. At the end of level 7, 31001 95031 LGCA appears. This is actually Imagic’s old address (P.O. Box 31001, Laguna, CA 95031).

Imagic held a contest in which you could win $1000 by correctly answering how many tridents are hidden in the Fathom ad (below) and on the back of a Fathom box, and having your entry card drawn.