Amazing game feel!
The idea of upgrades getting shown as auction while playing is very original, and you end up trying to buy upgrade really high just in case. Which does help avoid the issue of accumulating too much money.
The scaling as the wave went by felt a little weird. I got to the wave 60 without ever losing more than one heart but the boss insta-killed me.
If I had one feedback, it would be to reduce the strength of the screenshake as waves go by, because I couldn't read the screen at all by the end.
Overall very cool!
