I love this game. I kind of see it like a sybling to "Cursed Treasure".
One thing though. The indian guy is way over powered. I easily took down every level just using that class.
Just pick a spot with 3-6 spots around. Place an indian there and upgrade him with "invicible/speed". place other indians around him and upgrade them with "damage".
Place other indians around them when you have the money.
Watch the carnage...