Bubble Bobble - Nintendo Entertainment System NES 

Brothers Bub and Bob are two happy go lucky dragons living in a magical forest. "Baron Von Blubba" has kidnapped the brothers' girlfriends. Bub and Bob have to finish 100 levels in the Cave of Monsters in order to rescue them. At the end of the game after fighting Super Drunk on level 100 in cooperative mode, it is revealed that Bub, Bob, and their girlfriends are humans transformed by magic and that Bub and Bob's parents were kidnapped as well