Cool game! Good story. But neeeeeeeds speed button.
Polished, and bug free, but there is a problem with balance. Doing the math, the most cost effective tower is the wooden tower, which is also the cheapest tower, also as there is no scarcity in the amount of land, there is no reason to build any other tower except the wooden one and upgrading it.
I would suggest changing the towers to be appropriately different, also balancing the damage to be higher for more expensive towers:
Wooden tower: keep it the same.
Stone tower: should stun or do splash damage, also should have much higher damage but high cool down.
Fire tower: much stronger damage, low cool down but low range.
Magic tower: high range and damage, or gain mana with every attack.
The same goes for magic spells, because there is no cool down on attacks, it is most effective to just spam the lowest effect spell, higher spells should do more damage per mana used.
you have to buy two towers for the 2nd level. But it's a good game.
@samuraipanda2: To pass the 2nd level you need to buy that tower AND upgrade it. Or else it can't kill anything. I've played a lot of tower games and although this isn't as fast paced, only 1 game mode and limited features, it's decent.