Just starting on the main screen, going to options, and changing it to fullscreen works fine. Then the normal way to exit the menu (if not shown) would be to press ESCAPE. What does it do? It exits the game. Once you start the game, just trying anything besides what ends up being the spacebar is incredibly frustrating. The controls should be shown on the UI; if not, they need to adhere to more standard control schemes. These are nonsense, and having to work them out on your own gives the game a very short shelf life.
The controls are too frustrating to work out and I will move on to something else until there's an obvious change.