The glow really helps to set the atmosphere up, Loxmer. The game might be made only of shapes, but it still has quite a personality, and ends up being quite enjoyable to play.
Personally, I would've liked to have a run button, since for me the horizontal speed was a bit slow.
I hope you don't mind, but here are some thoughts:
- For platformer games in general, I think a good effect that fits a lot of situations is a squish when jumping. It really helps sell the impulse the character gets while jumping;
- I also think some SFX and a nice, wet reverb on them would be a great plus on the already interesting atmosphere.
Also, the Shift power up was quite interesting, since it also fills your blood as I think I noticed. The instant respawn is also quite welcome, since at least for me I died a lot 😅 got stuck at the second shift level, sadly.
TLDR: Really nice game! The shapes, glow, and other effects (such as the trail and the particles) really add to make it fun to play.