Thexder

Thexder is an arcade game that was a major cross-platform hit, selling hundreds of thousands of copies. Loosely based on the Japanese cartoon Transformers, it featured a robot that could morph itself into a ship. The Coco version, being originally released in cartridge format, only featured 5 complete levels, and no music, as compared to PC versions. On the other hand, it looked really nice, and was also one of the few games that was later ported to OS-9/NitrOS9. An interesting tidbit: From Alan's recoding of the game, it appears that it originally WAS written for OS-9 (internal calls were set up suspicously like OS-9 System calls, etc.), and only changed to RS-DOS at the last moment, probably to expand the market it was aimed at (no disk drive needed, only 128K needed). While Alan converted it, he also added a few options: Invincibility, and multiple speed levels (including some faster than the original cartridge version).