Shoot the incoming enemies to protect your base. Collect weapons and turrets that automatically fire on the incoming missiles. Push the turrets around the battlefield to take advantage of their range and abilities.
Keep your base safe from the huge advancing army using your trusty sniper rifle, air strikes and artillery. With each wave the invading army gets stronger, spend your money on the right upgrades and try to survive the war!
Protect the flora against the invading monsters by building your army of plants. Design your own path with defense units. Juggle the exit gates to confuse the incoming monsters.
The world suffers from oil crisis and you have to defend the last desert oil-base from the incoming enemies and armored vehicles. Earn experience points to get new weapons and don't forget to use power supplies dropped by allied aircraft.