itch.io

On most distros installing should be enough. Then you can simply run it. If you use wayland, you might have issues with getting to fullscreen it properly. Don't worry though, If you don't know what wayland is then you almost definitely do not have it.

If you don't know how to install it for your distro, just look it up.

You can run it with WINE! Works for me at least.

Also do note this works for any game that uses nw

Go to the website nwjs.io, download the version for linux. Inside the tar.gz will be a folder. Overwrite the contents of that folder into the main game directory, then launch with itch.io or directly via the file 'nw'.

I had that problem too, you must use the interact button (z) rather than the enter button and it should work

If I play the demo, is there a chance that I might miss things that get added in later?