Nice game
Drawing symbols is fun. However, sell and upgrade looks too similar, I accidentally sold a tower I was planning to upgrade.
Soul collecting... Now killing is not enough, you have pick up the souls. Well, you can't collect souls while placing a tower, probably intentional, but I did not like that.
Music... Fail. Darth Vader would say "Nooo!" and Lex Luthor "WRONG!!" Game has a word "Savior" in it. Demonic creatures crawl toward innocent townsfolk. You create powerful defense towers with small gestures. That means game music should be something like epic church music, not "wah-wah, wah-wah, wahwah wahwah wahwah wahwah..." This might fit better to some other game.
I still keep trying to beat the story mode. Good work!