Interesting little game. I tend to like tower defense styled games. The idea of upgrading your wizards is pretty cool to me. I feel like the wizards die really quickly once the enemy touches them though, despite it being a pretty slow game, making the healthbar feel mostly useless. Maybe adding a cooldown to the collision every time it deals damage or making it bounce back slightly each time it gets a hit (which would allow for the wizard to get in a last shot or two to try to defeat it) would help.
Pretty cool for your first game. Good job, guys!
If you get the chance, I'd like to see what you think of my submission!