Hey man! Good game, just few key improvements: it doesn't check for cost when repairing the ship, can be instantly fixed. The spawn rate could go higher over time. I wouldn't allow the player to put turret in the same spot. The spike would make much sense if you would have other type of enemy who is lets say faster
Good pixel arting, i love the thumbnail I hope you learn from this awesome little prototype and I will see you in the next jam!