Interesting to learn it was a special gfx mode. That explains why it ran at half height on most post 286/CGA systems and how it was so darn fast.
"Moon Bugs" came to be shorthand w my friends for anything fast, twitchy, and inexplicably pointless, like turning on the tv and seeing an explosion or someone driving by and yelling at you but being unable to understand a word.
Yes it was in the long, lost .com format - which you used to be able create on the fly with debug.com, found on every pc by default. IDE? Phooey! Just a list of segment registers pointers and data/code blocks and boom, off to the races. iiuc, no .com program could be more than 300k, bc they were 5 seg regs and each was limited to 64k.
That was when computers were still more bicycle for the mind than virtual exoskeleton.