Apple II version creditsThe author listed on the title screen of the Apple II version (Ben Serki) is different from the authors referenced in the game code itself (T. Nagawa & S. Beppu). According to the book High Score, Serki is the author of the Atari version.
VersionsThere is a rewrite of the game in the Seed7 programming language. There also is an unofficial DOS port of the game.
Information also contributed by Nélio.