There is definitely space for improvements but overall it was a nice experience! I think the early game could be sped up by granting level clearance once you destroy all the turrets, because when you do it's just a matter of waiting still in a "corner" of the arena - also I feel like bullets should despawn between two waves because it happened more than once that I got teleported right on a bullet at the start of a new wave and I couldn't dodge it.
Other than that though, it's a really well made game :)