GTA: Demons Vs Fairyland
The fairies were minding their own business and living peacefully. They are happy with their own lives and let the mortals do as they pleased. That pisses off the demon and they want the fairies to suffer. One day, they kidnap the children of fairies. The fairies quickly retaliate by sending their troops to retrieve the kids. As much as you like to be the good guys, you won't be in this game since you represent the demons. You would need to make sure that the fairies don't get back their children. Each fairies you kill earn you money. You can use the money to buy another tower or upgrade the existing ones.