If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Use your cannon to annihilate wave after wave of stickman onslaught, changing your cannon's aura to that of incoming enemies to destroy them.
Mouse - to aim and shoot.
A - Earthquakes.
Space bar - Drone strikes.
Z/X/C/V/B - Change colors.