Hoping for a Linux build as well :)
Let me know if you need some help with it, using Godot myself (on Linux)
Just tried the demo on Steam, and I must say I absolutely love the art and music. Great job! ;) It runs very well in Linux under the FLOSS AMD drivers and it detected my XBOX controller without any issues, too!
Now, the difficulty of the demo must be quite high, as I have a hard time in the second level to make the jump off of the platform. (I think I managed twice in 100 jumps, lol).
Definitively can be rage-inducing ;)