I like the monochromatic style. It's a little hard to see what's happening, but that feels more like a feature than a bug. Looking at your GDD it seems that's exactly what you were going for and I think you nailed it perfectly.
The jumping and boosting is cool. I couldn't get it to shoot, but your note says the web export broke some stuff, so I'll just assume that it was super epic.
I like the sun/heat mechanic. Hiding alchemical symbols throughout the HUD/UI is rad.