Cool game idea, but I think the game difficulty is a problem, it is VERY easy. Which is usually ok for a gamejam, but since the goal of the game is to die, get upgrades to start again stronger, the fact I spent 10 waves fighting enemies that can barely touch me, that I already one shot them and the map is covered in health pack, I kind of don't feel the need for upgrades since I'm already strong enough. I think having it easy at the beginning is ok, but I feel wave 10 could've been like wave 3 instead, so I can die, buy some upgrades, start over and feel stronger. I ended up purposely dying so I can try the upgrades, spent my money and couldn't really tell the difference.
The concept is cool and the art is great, it only needs some balancing.