Clicking on StartGame does not work beacause the button is not wired to anything:

  func _on_StartGame_pressed():
      pass # Replace with function body.

Probably not ready for the public, but fun to hack around and trying to understand how it works from the inside out.

The level editor works. So I guess there might not be any levels. But you can chuck down some tiles and then make Tux jump around. Works pretty well to be honest.