If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
You, little GunMaster, must defend your ziggurat. Enemies on every side! Keep defending; grab those powerups and ammo that fall from the skies, and fight the good fight!
WASD to move;
Mouse to aim and fire.
Spacebar to jump.
See game for complete controls.