Use bombs in each level to burn the wooden blocks with fire or rust metal with water. Complete all the levels in each elemental world, fire, water, sky, and earth, each having their own unique gameplay styles.
Survive for as long as you can as you fight through hordes of alien monsters. Grab new weapons that appear from random crate drops and earn money which can be used to purchase attack towers and health.
Things go terribly wrong when you decide to take a short cut through an abandoned park. Now you must fight off hundreds of evil mushrooms and take on powerful bosses. Survive each wave and unlock upgrades to make you stronger.