The alien invasion has begun! You control the last platoon of soldiers that have survived the onslaught. Protect your bases over 5 stages across the USA. Once all the bases are destroyed the aliens will control everything! Each stage consists of 4 waves of aliens, each wave stronger than the last. At the end of each stage there is a terrible alien monster to defeat! Each time you kill an alien gold coins or ammo are left behind for you to collect! Use the gold to buy extra soldiers or upgrades! Place your soldiers near your bases and they will protect them. Controls: Command your soldiers to aim and fire using the mouse. Roll the mouse cursor over dropped coins and ammo boxes to collect them. [SPACEBAR] = Purchase more ammo.  -  = Quickly purchase one of eight troop types. [Q] to [T] = Purchase one of the five upgrades.