The double jumping is strange
You can use it right at the beginning of a jump, smashing space twice, to get one big jump. You can use it at the top of a jump and it feels like a usual double-jump. You can use it at the end of a jump and the double jump does nothing. I suspect this is because the double jump is something like a velocity.y += constant
If you start a jump with A or D, you can change directions by double jumping while holding W or S, but you cant reverse your direction with D or A. If you start a jump with W or S, you can reverse your jump direction with S or W, but A and D do nothing. You are locked in a straight line.
Going from a flat plane to going down a ramp will always leave you airborne, practically disabling all of your controls, including double jump because it barely does anything when going down. Going from a upwards ramp to a flat plane does not have this issue.
If I do manage to cross a few obstacles quickly, I turn around to find that all the ground enemies walked over them quickly as if it was flat ground. The only way to get distance between you and your enemy is to hold S.
Pickups in general are difficult to see. I'm not sure if the grenade projectile has a model, I never see anything but the particle effect if its rolling around on the floor. I don't know what the purple power-up does, but I'm guessing its quad damage since its the quake quad damage sounds. Picking up a purple power up does display some "rip and tear" tier text on the screen, I don't know why this text couldn't just tell me what the power-up does. (note: i now know its the mask of madness but I still dont get that in-game)
Death screen doesnt have a quit to menu or quit to desktop options
Slow motion is useless. I never feel like the limiting factor in a situation is how fast I can react to things.