I'll extend some things and edit some more:
- I retested it because I thought of a way to see if the "wrong" collider was in the ball or in the wall and now I think it's in the ball (cause even the buttons have the same quality, so I'm guessing the ball collider is a square that sits inside the ball?)
- also about the colliders, if you slam yourself in some walls (for instance after opening the first door you can go in the room you just unlocked and slam the ball on the wall where the now open door is) and then try to run across the wall, you'll sometimes get stopped as if there's a bump in the wall. If you smash into the bump a couple times it disappears, but if you go away from the wall and you again smash into it and try to run it's gonna be there again. Not necessarily in the same spot, there's usually a couple per wall but, but it's gonna be there. This also interacts badly with the momentum, because if you get a bump when you're trying to accelerate back you get stopped again for no reason. It's just negative feedback for the player, mainly.
- if you decide to remove the momentum, you should probably speed up slightly the bullets (the difficulty in maneuvering your character balances out the slowness of the bullets, but if you suddenly can make a U turn without losing speed then the bullets should fly faster)
- another thing I haven't mentioned is the enemy AI. Making a detection system for it that doesn't aggro on the player from the other side of walls could open up some interesting positionings (because they wouldn't be behind the walls waiting for you), but I guess that since they disappear once you change the difficulty and you mostly have to change it to get through doors it probably doesn't matter much. It's worth a thought, I guess.
