All the levels are unlocked and you are given a lot of money to start with. All upgrades will give you more money rather than take it away.

They are not aliens, they are not bugs, they are monster trucks and they are out to destroy the town. Play Monster Trucks Attack flash game and defend the city. The trucks will be coming in waves so stop them in their paths by throwing them around for maximum damage. Upgrades will be given to you as you earn more money.