Hold space to accelerate downward and destroy blocks; the faster you accelerate, the more damage is done to blocks. 
Every few seconds blocks more blocks appear from the bottom of the screen. Don't let the blocks reach the ceiling. 
The more you hit blocks, the higher your special meter gets. 
Once your special meter reaches 100%, you start accelerating super fast and it shrinks back down (not perfectly implemented).
After your special meter is depleted, your power increases by a tiny bit. 
The game lasts forever.