I really like this game. The tower leveling system is pretty solid and the skill points are well done.
However, the towers could be slightly better balanced. The crypts are a bit OP and level far faster than the others (despite skilling up that area for dens and temples). Temples level extremely slowly unless they're at the very very front.
And I hate the meteor spell. It's a tower game, not a shooter; using meteor is like a shooter. The other two spells help your towers and tower building.
The upgrades are poorly worded (poison doesn't upgrade all towers with poison damage as stated in game, it upgrades all poison towers). Kind of silly to be able to get all upgrades by the end of the game.
Leveling towers is a nice idea but it's very poorly implemented. 1/5.
Targetting of towers is way off. Kind of generic. Would like a more dynamic upgrade system other than just range and reload (range is seriously cheap and reload way overpriced). May be nicer if could decide how towers upgrade versus generic +dam.
Physics are wonky, they start spinning for no reason. Pieces have no weight when sitting but if tapped they go flying. The pieces not in use are extremely aggravating. And the outline is extremely picky about location.
Zooming is annoying. Sometimes lost time even though i was aiming at target. Also lost time at first because I thought I'd have to control power and angle of shoot rather than point and click (would be better as a gun since player is not).