An upgrade heavy tower defense game. Use three towers each placable on corresponding landscape features. Crypts on snow, demon towers on rock and dens on grass. Dens correspond with orc upgrades, crypts with undead and demon towers with demons.
Try to keep pesky humans from stealing your gems.
Unlock upgrades in the skills menu. Reach achievements for bonus experience. Try to get brilliant ratings in each stage during night and day. At night you can only build near your cave and other towers.