Killheads is great combination of zombie shooting and 'match-three' puzzling with an atmospheric (and bloody!) horror theme. Match up and pop the monster heads before they reach the barricade. Use grenades to get out of a tight spot. Killheads has thirteen levels of relentless head-popping action and an online leaderboard for the best completion times.
Aim the cannon with the mouse. Use the left mouse button to fire heads. Match three heads in a row to pop them. Aim within a crowd of heads to use a grenade (indicated with a large cross-shaped cursor).