Nice work, exciting this is your first fully completed game! Impressive to to have done all the modeling across everything in that amount of time too.
Definitely posed a challenge, I was getting close to completing stage 3 or 4 I think it was, but jumping between the walls and having to restart all the way back at the beginning without checkpoints made me skip trying “one more time” to move along. I don’t think i fully understood how to use or hold onto the powerups, maybe it’s intentional you only have it for a moment?
As others mentioned, the platforming is a the challenge here in 3D, since a first person view you can’t see how close you are to the edge. The jumping felt a bit “floaty” and holding space made you jump farther, but made it also harder to judge how far you could get.