Hello Sayanel! Thanks for trying it and your suggestions. Right now spines which hit produe a small particle and enemies briefly flash white (mostly visible on ghosts as they have some HP, whereas bats have 1 or 2 I think). Maybe I should make the particles bigger or add some sound (which I was a bit afraid of doing due to the sheer volume of bullets). Do you think player also needs more feedback on top of sound and screenshake?
In my opinion (so take it with a grain of salt), I do think the ennemies more than the player needs more feedback.
I can only suggest you The art of screenshake. It is 30mn long~ but the tips given in this video would -in my opinion once again- synergise very well with the feel of your game. So something like a small freeze when hit, random bigger explosion and permanent impact when hitting an ennemy.
