Youjuu Kikou-hei WerDragon (1989)

Following the disappearance of S-City under a wave of dark and stormy clouds, the Roland Federation sends their elite troops to investigate and return order, only to become prey for the now mutated inhabitants. Kai Karze, the lone survivor, finds himself besieged on all sides, and even he's begun to transform into a demonic being the longer he fights. He must quickly locate and destroy the evil force transforming him and the city into this nightmare realm before it's too late. WerDragon is an auto side-scrolling, stage-based action platformer with character growth and a dark science-fantasy setting. Kai will level up once you've destroyed enough enemies, gaining extra health and new abilities in the process. There are a few extra weapons to collect, devilish boss fights to survive, and many richly animated levels and cutscenes to enjoy.