Play the game using your mouse. Kill all the attackers and upgrade your gear by pressing space and visiting the shop.

Cities collapse into chaos as the Ravager virus mutates all infected into bloodthirsty Ravagers. You and a handful of others form the Last Line of Defense, pooling your remaining stockpile of weapons, special ammo, bunker defenses, and superweapons to fend off the onslaught. Survive 25 waves of Ravager hordes and keep your bunker from falling. If your bunker falls, the Line falls. If the Line falls, humanity falls.