Hit Enter. The buttons in the launcher window are not displayed properly if you have your Windows font size set to medium or larger. You should be able to just make out the top edge of the 3 buttons at the bottom of the window; the left button (Play) has focus by default, so you just need to hit Enter to start the game.
Hopefully this will get fixed in tomorrow's update (which, BTW, contains enough changes that it is unlikely to maintain saved game compatibility).
