It's a nice basis for a good game.
I think it deserves to be expanded: More exploration features, things to discover, upgrades,... We want MORE!!! 😅
Also, I didn't get why you included a "double fire-rate zone"? It discouraged me from exploring and incentivizes to stay at the beginning to sustain the waves of enemies.
It's a great feature, but it must be used differently to encourage players to push further, instead of backing off.
All in all, good job 😉