This is a very good game! Simple but hard to master.
- There is a bug sometimes that makes it impossible to buy towers. You can still destroy them, but it's impossible to buy more. You end up with a gazillions orbs around you.
- Late game, you can get to a point where it's almost impossible for the creatures to reach you, but the game keep throwing them at you and the frame rate drops a lot. I had to suicide after getting something like 1 frame / second :) Maybe add a new enemy late game that can destroy walls slowly? Or an end game with something to build with the orbs?
- The "harvest" upgrade is a bit OP, you don't have to take any risks late game.
Keep up the good work !