Match four pieces, and one of them will glow. If you match it again, it will clear a row or column that that it is connected to. Line up a five item match and one will change into a grenade. Connect it with a nearby piece to destroy all similar pieces on the level.
Power-ups
The following power-ups can be purchased to help clear levels.
Bodyguards: Protects you when running out of moves.
Grenades: Clear a section of a level.
Sniper Shots: Kill zombies that are in your way.