Bubbles fill the screen and you burst as many as you can to reach the next level. It is a fast arcade toy rather than an idle game, with a timer, a target and a score, and it asks for attention in a way that almost nothing else in this catalogue does.
Levels get busier rather than smarter, so how far you get is a question of how quickly you can move a pointer. There is not much beyond that, but it is a clean five minutes and it does not pretend to be anything larger.