Nice idea and really good presentation!
You might wanna make a tutorial or highlight the crates better, beacause I played like 10 times before realising you can interact with them... But the customization was definitely fun! I once got a combo like x2-x2-x2-Tripple Shot which felt amazing, so I think combos should be expanded upon
Also I think a map would be really cool to know if there are still potential crates somewhere
Also I thought it was weird that bullets deal 2 damage... that means you sometimes die really quickly which felt a bit unfair