MEGA MAN / U.S. Gold / Game Gear
Capcom handed the Game Gear version of Mega Man off to U.S. Gold, and basically all they did was chop out various levels from Mega Man 4 and 5 and mix them back up into this game. You start out with 4 selectable stages - Bright, Stone, Star and Napalm Man - and when those are done you go through Dr. Cossack's fortress, which is actually repurposed versions of Wave Man and Toad Man's stages, then Wily's fortress is Quick Man's stage for some bizarre reason.
The game looks almost identical to the NES versions and sounds decent given the more limited GG sound chip. Gameplay and level structure has also been faithfully recreated, though the smaller GG screen makes some of the harder jumps even harder than they were before, and there seems to be occasional frameskipping or general slowdown/choppiness for just a second here and there. It's still perfectly playable and a fairly high-quality port on the whole, though, if a kind of weird and random one.
* Gameplay Video