Runes and magic
Demons want to plunder your lock. Place protective towers so that to beat off attacks of demons. Use also magic spells. But main not quantity a tower, and correct tactics of arrangement! Improve towers, strengthen their fleeces of various elements. Mana receive for the killed demons. The special radar will notify you on quantity and force of coming demons. Management in game by a mouse. In game there is a training, pass it that it is better to understand features of game.