Monster Time is basically Burger Time. Only with monsters. And no burgers. Still plenty of time though.
The screen is a jumble of platforms and ladders with bits of each monster scattered around. Walking over a monster piece drops it down to the platform below and eventually you'll reassemble each monster at the bottom of the screen.
Getting in your way are, er... some other monsters. Smaller ones. But they'll chase you down and you're dead if they touch you. You can zap them with a laser or pour acid on them. But they always come back.
Oh, and there are Castlevania and Ghosts n Goblins themed levels.
Monster Time [Newgrounds]