Silpheed

Silpheed is an arcade game that was a cross-platform hit. It is a 3-D space game, with 2 distinct levels: flying through space, and flying through a trench (similiar to The Force). It was much more complicated (and faster paced), as there is all kinds of powerups that you can get to increase the capabilities of your ship, including shields, various weapons, and more. The Coco version was on a "fat binary" cartridge that contained both the Coco 1/2 version, and an enhanced Coco 3 version. Unfortunately, due to the decision to make it one cartridge, it had to be severely reduced in size to fit (both versions had to fit on one 16K ROM), and a lot of the extra features that the DOS version had are missing in the Coco version.