Thanks for the very detailed comment!
And i agree with you that the player getting hit is indeed not noticeable enough, although i only really thought of this after the jam was done ;p, so i did not have time to fix it. because currently it only plays a sound, and makes the screen shake a bit (but that's almost unnoticeable according to the people I've talked to so far).
as for the warning, I've already created a new version of the game that has a warning on the menu, as well as two new buttons to change the bloom and remove the background, the explanation text on the menu also doesn't have bloom on it so its much more readable than it is currently. but sadly due to the way the jam works i can't upload these versions to itch yet, but these changes are available on the git repository.
Also the backgrounds moving speed (not the colour changing speed) is somewhat tied to the music of the game, as the weird... wormhole type thing opens/closes with the beat of the music, but i agree that changing the speed that the colour changes might be a good idea if i make any more changes to the game after the jam. same for the idea of making it react to the players movement/position. i actually tried to create some 3D fractal art at one point during development but this seemed like even more distracting than what we currently have ;p.