Very atmospheric, very Iron Lung. I loved the intro, it felt very professional.
On my first attempt, and this is on me for not reading the description first, I jumped right in and was confused with the number system. I didn't realize the player was moving before I closed out and came back in.
It might help to rebind the keybinds to the conventional wasd, space for up, and shift/ctrl for down just to tap into that pre-association people have with those keys if you didn't want to address it more directly.