ok, couple of things:
atleast it can be opened now... but, zip doesn't have any of the background music ogg files.
also on GUI_on_Mesh.gd:
199 styleActiveSelected = preload('res://ButtonOutline_Selected.tres')
200 styleSecretSelected = preload('res://ButtonOutline_SF_Selected.tres')
these lines had typo (lowercase s in selected) so they couldn't be loaded.
as for the game... now that I got it running. you might want to concider changing the controls to regular wasd + mouselook kind of thing.. because as it is, it feels weird. turning is slow, and requires mouse button to be pressed when looking around, and still you can't look up and down? feels very unresponsive.
oh. and I did fall couple of times :)
.b