Photon Baby is an excellent puzzle platformer, with NES-ish graphics and an interesting puzzle style. You play a little fellow with a sort of gun; while babysitting, the child you were caring for was kidnapped by a vampire bat, and you evidently have to fight through thirty platform levels featuring vampires and bats to get the brat back.
Vampires wear differently colored capes; some surfaces of each level are colored lines. You bullets are gray when fired, but take on the color of one of these lines; and a vampire can only be killed by a bullet the color of his or her cape. This is where the puzzle aspect comes in; you must figure out how to slay each vampire, given the organization of the level, and the positions of the colored lines.