Nice tower defense game with upgrades. I liked the overall gameplay loop and especially the upgrading. Here are a few things which could improve the game:
- Some music would be really cool. The current sound is a bit repetitive
- I would show health bars (or something similar) for the enemies and your turrets. This way you see when they will be destroyed
- Using ESC for back is not the best option, as at least for my browser I leave the full screen when I click on ESC
- Would be cool if you can directly upgarde something after the first level. Or maybe it was just because I played very bad in the first level :)
Congratulations to this nice tower defense game!