Limbic Software has Tower Madness 2 (iTunes Link) for the iPhone and iPod Touch in the iTunes App Store for FREE (regularly $1.99) for a limited time.

The aliens are back, and this time they’re on a mission to turn your beloved sheep into sweaters for their emperor! The sequel to the hit tower strategy adventure TowerMadness is finally here. Protect your flock using quick thinking and an arsenal of awesome weapons.