Cool concept, good TD game :) Some things to consider for enhancing: adding projectile and damage feedback, the shop with this solution is not very good to use as it blocks out a huge chunk of the screen, also the in the upgrade menu (as others wrote it as well) missing an UI display for available money. Overall well done for a one person team in 10 days, congrats!
If you have time, I would really like to hear your thoughts on our game and get your rating ;)