You have 185 seconds. That is slightly more than 3 minutes. Move the cannons with the arrow keys. Shoot a harmony stone with Ctrl, If there is a collection of 3 harmony stones, you can click them, it will give you points, and they will dissapear.
Types of stones:
- Elements of Harmony: Group and click them for points
- Ereaser (horn): Click, and this block, and the one's adjacent to it will dissapear.
- Block block (X): Does nothing, except being in you're way.
- Surprise block (?): Becomes a random block.