Playing with your mouse, you have to kill all the monsters on-screen. To do so you have to remove blocks or pop bubbles by clicking on them, alternatively slashing through chains with a sweep movement. The point is to work out the sequence required to get all of the monsters. There is a difficulty curve, but it steeps slowly over the fifty levels. If you enjoyed the rest of the series, you'll be all over this. And if you haven't, but like the idea of some physics-puzzle fun, give it a play!