Description：Welcome to the elite fighting unit, the SAS. Now you have new guns, an in depth leveling system, five maps and so, so much more awesome! Earn money to upgrade your defenses and your guns. As levels progress, the waves of zombies become harder and harder to repel. \ \ Arrows or W,A,S,D to move. Space bar opens your inventory. Click mouse to shoot. Press F to fix damaged barricades.

Instructions：