Nice job creating the beginnings of a turn based tower defense game!
I had some trouble grasping the game mechanics at first.
Initially I placed all the turrets at the bottom, but then realised enemies were spawned at the top and had to reset. I didn't realise at first that I also had to shoot during my turn - I thought the turrets would auto-shoot somehow. When holding a turret to place, you can't shoot at the same time.
Eventually I figured it all out - but letting you know what issues I ran into in the beginning.
The visuals of the game look really great. Awesome job at creating an initial UI as well.
Great job at creating a game and submitting!