Very fun and challenging tower defense game!
I liked the clean UI and cute style. Also interesting storyline.
Each level starts off "easy" but things get hectic really fast and you have to think quickly to avoid getting overwhelmed by the rush of souls.
I managed to clear level 1 after 4 tries. Level 2 cleared in the second try!
Improvement suggestion: Add a tooltip when hovering over a tower to know its stats. Something as simple as shooting speed (fast, normal, slow, very slow) and power (weak, medium, strong, very strong). This helps a lot to set your strategy of when and where to place each kind of tower.
Great game!