Sorry· I could not figure out out start the game. I could navigate the menu (tab and arrow keys) but enter did not start the game.
What OS are you using?
I am running Linux
If you need really need want to, you can open the project file from the "Assets and Project File" and run it from the Godot engine
Use Z instead of enter (I modified the original Godot ui controls)
Should have probably made that more obvious... sorry!