Someone somewhere up there said to edit out tie games. Now if you do that, most of the portion of the audience that's paying attention will notice. They might not notice Pat Sajak's never spinning Bankrupt anymore, but everyone knows that tic-tac-toe is easy to tie. So as soon as a game gets to the point where one player can win and the other can only hope for a tie, you've lost them.
So either you have to make a rule preventing ties, or leave them in the show. The 5-square rule is already on Hollywood Squares, and at this point that show's enough well-known that to steal one of its original rules would just make it harder for Tic Tac Dough not to look like a celebrity-less, comedy-less ripoff. And off the top of my head, I can't think of another good, simple rule to prevent ties.
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I'd like something more skill-based for the bonus, and more with the theme of tic-tac-toe, but still keeping the Dragon (new graphics, old roar! That was the worst part of the 1990 dragon, at least until he learned to rap). How about something like (I think) Trump Card had? Pick a numbered space, answer a question, get an X for a right answer or an O for either a pass or a wrong answer. Put the Dragon behind one of the spaces with the usual result. Three X's in a row wins. Adjust the question difficulty and maybe add a timer, depending on how often you want a win.