Start up the game, then when you get to the list of levels/trees press Esc. That opens up the menu. Now, what you need to do is move your invisible cursor to the upper left and click on the "Fullscreen On" button. That turns Fullscreen Off and, for reasons known only to game devs, it makes your cursor visible again. This does mean you can't use Fullscreen though, since turning Fullscreen back On makes your cursor invisible again. No I don't know why this happens, but I suspect you could use this same trick for other games where this happens. Maybe.