All upgrades are free.
THE SECOND WAVE HAS COME! Now includes 25 new waves in a new environment. Also includes brand new premium weapons and upgrades to help the cause. 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 50 waves of Ravager hordes and keep your bunker from falling. If your bunker falls, the Line falls. If the Line falls, humanity falls.