The target of this game is to kill every monster in less than 90 seconds to gain next level. You control a little crab, and you must push bricks towards your enemies to kill them. If you push a brick and besides it there is another one, the block you pushed on will be destroyed, maybe dropping a bonus. Bonuses are various, and someone has a particular function (For example: Lightning will destroy every monster on the screen).
Not all bricks can be moved. Each level has three special blocks, and when you put them together, you gain a special multiplier bonus (2x or 3x if you put together two or three blocks).
Look out for monsters that follow you and good luck!!