Very cool game and unique mechanic to be able to fully customize the gun! I also liked the graphics and the overall feel of the game. Sometimes it was a bit hard to get the upgrades, workshop and shop to open. You had to be standing at a very precise point to be able to press tab. Maybe there the hitbox should be a bit bigger. The death animation also felt not so strong. There I would have wished that you die in a bit a more impactful way, like the exploding enemies. Currently I was a bit confused for half a second when my caracter was not moving and then I realized that I died. At the moment (at least for me :D) the difficulty might be a bit high and I wished more upgrades spawned, so that I would be able to customize cool guns as early as possible, because this is the unique point of this game.
Congratulations to this innovative and engaging game! I had fun playing it.