Apple II version credits
The 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.
There 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.