I found the most OP strat instantly. SPOILERS: To just spin the hammer at light speed until I got tendonitis which basically just made it so I had to run into enemies. Got so much money so fast that I had all the items (that I don't know what they do) right away. The only times I took damage was when I didn't see the falling rock out of disinterest. I played wave 10 expecting something to change but it didn't so I gave up after.
But it feels ok and it looks very pretty. A lot of games feel like they have stiff sprites when they're drawn like this but the animation really made them pop and felt fluid.
I love that items feel like they're in the world. I always want that in games, never stop doing that.