Can't open a menu (from the start), eventually got stuck with an arm. Found the leg but can't use it because I can't swap to other objects.  At some point in which the train darkens to pitch black I couldn't even use the flashlight, and by chance found out there was a night vision by hitting every button I could after stumbling around for 15 minutes in pure void.
Good luck I'll just stick to watching it on twitch.
I only happened across this page trying to google anything. Nothing is on steam whatsoever. 

Hey man, thanks a lot for trying out the demo!

As for your complaints, you'll be glad to know they're all fixed in the full game.

By the way, you CAN open the menu, but it's on the M key instead of Escape. I've added the possibility to alter every key in the settings though, so you guys can customize them.