Interesting idea!
I'd like to see more variation in the gameplay. At the moment, you only can move. Giving the player another action like swinging their weapon with a button or even a simpler method of movement like clicking could help the game be a bit more engaging.
Upgrade tree is always interesting, but be sure to be clear about cost/reward. You use 1/50, 2/50 etc. to denote your shop, but that format isn't universal. I was confused my first few runs because I couldn't figure out what it meant!
Great job finishing, and best of luck to you!