Stop the invasion before the enemy reaches our cities! Alien life forms have been detected and our army has mobilized its defensive tower forces to protect us.
Use towers to build a labyrinth from entrance to exit. Each tower can be upgraded 4 times. With each wave, enemies will become stronger, so use money you earned to upgrade reasonably.
One last turret stands between you and total annihilation. Destroy all malevolent alien ships by upgrading your cannon and building the ultimate killing device!
