Here is video with your game! 

The good parts:

• the fire vfx is top notch, feels good to use the flame because of it
• the watery bits and the bullets look nice and shiny

The parts to be improved:

• There’s this one specific look with a gradient background and vignette and a certain amount of bloom that makes games look nice but so extremely generic (because at some point every aspiring dev attended a meeting and decided they will all do exactly that). Play around with post processing and find a style for you that sets it more apart.

I think this is a competent execution of the mechanics, doesn’t overstay its welcome - though I think you could cut on 1 or 2 waves and go sooner to the boss.

The fun part of your game is the flame, and I feel a bit “too good to use” because I feel like I don’t have enough coal to keep using because boxes feel like they’d be limited… maybe try to find a way that sends the player to use more of the mechanic that is really cool instead of limiting it a bit too much