Mega Man: Dr. Wily’s Revenge GAMEBOY

Mega Man: Dr. Wily’s Revenge, released in 1991, was the character’s first handheld outing, and rather than adapting one specific NES game, Capcom built it as a “greatest hits” remix — four Robot Masters are pulled from the original Mega Man (Cut Man, Elec Man, Ice Man, Fire Man) and reused as the game’s first stage bosses, with new levels built around them.

The back half of the game is original content: after clearing the four familiar bosses, Mega Man faces four brand-new Robot Masters created specifically for this game — Enker being the most notable, since he’d go on to reappear in later entries as one of the recurring “Mega Man Killer” sub-boss characters. The Mega Buster charge-shot mechanic from Mega Man 4 onward isn’t present here, keeping the core shooting closer to the original NES game’s feel.

It sold well enough on the Game Boy’s strength as a portable to justify three direct sequels — Mega Man II, III, and IV — each following the same pattern of a handful of returning bosses mixed with new ones, giving Game Boy owners a semi-original side series running alongside the mainline NES and later SNES games.