A secret mission at the end of the game is accessible by typing in a password mailed by the software company after the player completes the last registered mission and receives a number code. The code is then mailed to "Project Halley" (in reality the software company that designed the game) on a pre-packaged postcard. A letter is then received from the software company instructing the player to load the program, initiate the Starbird level, go to Earth, and type MINDSCAPE to access the secret mission.