Thank you for playing and thank you for your feedback!
Agreed on the player bullet particles being a bit on the nose (though grenades essentially blinding you when firing quickly is intended).
Having the upgrades change the weapon to act differently (ex: shotgun, rocket launcher, etc) would've been an interesting path, but we ran out of time. On the plus side having a lot of grenade upgrades turns it into a grenade launcher and a lot of multishot upgrades makes it like a shotgun (and a lot of rubber upgrades makes you lose :'D).
Glad you liked the scaling and the game overall! <3