Few complaints:
If there's a pause button I haven't found it, it would be great to have one to take breaks if you're on a roll, not make sure I have enough time for a run.
The camera is hard to work with, it would be nice if it we're more zoomed out. Where it starts you out it seems too close and bullets come out of nowhere and near the borders everything is very small, making it hard to see some enemies and judge the massive distance to reach coins. I would be nice if it was constantly somewhere between those two and followed you around. Maybe you could have a minimap showing where you are in relation to the center w/ the turrets.
More upgrades would be nice, but idk what. Maybe if you add a minimap have map upgrades so the map can include a radar beyond your view that shows where enemies are.