The Real Ghostbusters (1993)

The Real Ghostbusters, known as Garfield Labyrinth in Europe and Mickey Mouse IV: Mahou no Labyrinth in Japan, is a puzzle/platform game. The story is very simple: Venkman (or Garfield and Odie or Mickey and Mini Mouse, depending on the version you play) walk over a bridge one day, a tile breaks loose and Venkman/Garfield/Mickey falls down a deep pit, which ends up in a bizarre labyrinth, which Venkman/Garfield/Mickey must escape. There's no other goal apart from that, the player just needs to find the exit in each level. Apart from getting there, the exit must also be unlocked. For the latter, the player must collect all gems in the level.