BALL STUCK! BALL STUCK! Just kidding, I did it on purpose.
I like how the movement is unique.
Neither the spikes nor the slimes could hurt me for some reason, unfortunately. Also, I could somewhat cheese it by launching myself through walls in order to reach orbs.
The bullets being physics-based doesn't seem to hinder the player much -- so what if they can push some boxes around? If you make it such that you're meant to avoid toppling the boxes (and your bullets have much more inertia/mass than you so that you don't accidentally topple them while moving around), I think it will be more interesting. Or maybe the bullets should propel the player backwards, hindering their movement, like this godawful chaingun.