All that's really needed is better alignment between movement and camera; ex: I was holding Up-Left but from the perspective of the camera, I wasn't moving left at all, same with Down-Right vs right. If you give the player the ability to control the camera on top of that, you could probably get away with having some harder patterns/enemies/arenas, but then you might also want to have better camerawork at the edges of the arena (such as fading/dithering the material to let you see through it). The highlight through walls effect is cool, but if you're moving around the edge of the arena, the screen can kind of flash as it passes through each wall, which makes it a little harder to keep focus and gauge distances properly. It wasn't too noticeable in the jam iteration as you didn't have much reason to move that far back (though I did run into it when dashing to safety while getting used to the controls), but I would think that wouldn't be the case with more camera control.