Click on the empty tiles to the left to construct buildings, use them to defend your base from enemy and to produce units to attack them. All structures are upgradeable, which makes either them or units they produce more powerful.
Create a maze out of your towers to defend against 49 levels of advancing creeps. Five different towers with five Upgrades each including distinctive elite towers.
Keep track of the incoming and outgoing traffic of a busy airport! Guide the planes and helicopters to a safe landing, making sure to avoid any accidents!