Awesome game! I didn't get nauseous or anything, so that's good. I know you want it to be about accurate, precise platforming, but in its current state the lack of good air control is terrible. I keep making jumps that are almost good but if i could just shift a little bit more in the air they'd be good, and i wouldn't have to keep retrying. Otherwise, excellent game! I'm also making a first person platformer, so this was fun to try out and see how other people are doing the same thing.
It is actually possible to control your character while in air. It's just very subtle to allow you to correct jumps over longer distances.
Balancing the air control was a bit tricky. Previously you had much greater control in the air but i soon discovered that this introduced an exploit in the game which a player could easily take advantage of. (Basically it was possible to do a wallrun, jump off the wall and strafe back to the same wall while being in air and doing a walljump again and gaining height while doing so.)
So i reduced the air control to make this exploit impossible but give the player still enough room to correct his/her jumps.