I played this game a few days ago, and I came back to it a second time because it is really fun (also I forgot to rate it)! Unfortunately, I cannot make it past wave 2, I just get so battered on wave 1 most of the time.
I feel like part of the difficulty (on normal at least), is the scarcity of wrenches which helps massively with enemies and dealing with projectiles. Maybe also have throwing wrenches destroy bullets in their path as well as enemies?
Regardless, its such a fun experience - great job!