The built-in layouts usually put up "Game Over" when the tournament ends (not after the last level, but after the last player busts out). You can simply edit the Blinds cell (that's usually where it is, since there's no need for Blinds after the tournament ends), and click through the various property sets. In the Contents you'll see the Game Over message, and you can just click the Contents to edit it, and change it to whatever you like.