As far as anyone knows, humans are the only animals that can create fire. There's a very good reason for that: The planet will erupt in flames the second that some cute woodland creatures get their hands on the scourge of Prometheus. It's not just the cuddly animals that are the problem, either. Look at the knowing smile on every dolphin's face. It's a mercy that they live under water. Need more convincing that only humans should handle fire? Consider Fire Busters, an action/puzzle game for iOS. If you don't stop the nefarious "arson cat," his neighbors will wind up living in a charred wasteland.
Tower defense games are a dime a dozen on the iPhone, and many of them are great, but Bugs Wars manages to be the most unique of them all due to its somewhat more hands-on approach.