This was a great game! The risk-reward aspect was pretty cool, and it was something I haven't seen in any of the other games I've played -- basically giving players incentive to jump into the mass of bullets in order to get points for upgrades, yet risking taking too much damage and dying. It was a great take on the topic! Also, I really liked the music, and the sound effects and particles were done really well!
My only issue with the game was that opening and closing the shop was a little difficult. I think having an option to bind it to right-click would be a good idea. That way, players wouldn't have to reach over to press V and then B from WASD.
Other than that, really nice job!!