No sound at all? I use miniaudio.h for output which explicitly supports everything except pipewire, which should have an ALSA fallback anyway. I don't actually have any handling for if the audio fails to start though, maybe I should add some. What distro are you using? And if you try running in the terminal does it say anything about the audio in the output?
Heh, I don't know what's with the shotgun, even when I playtest I used to run past it a lot before the new lighting. I think it doesn't contrast enough with the garbage can.
In the case of the RL tunnel that's intentional, it's supposed to be a secret. There's a lot of dark parts in areas you don't have to go to, but my monitor isn't very fancy so darks come up very bright for me making it hard to tell.
I'm not really bothered by people getting a bit lost, I'd rather have people have that feeling of "ooooh, that's where it is" instead of whipping out the yellow paint, so as long as you found it without quitting I'll call that a win.
Thanks for playing, glad you liked it!