I wanted a ‘family feud’ style gameshow in keynote, but it was a bit complicated trying to make the ‘right answer’ appear. I found the best way to do it was to have 25 slides of all the different possible combinations of hidden/shown answers, then a heap of hyperlinks between various slides depending on what answer was picked. It worked out well.

To change the answers, go to the master page, and edit the text fields that have the answers, be careful not to move any fields around, just edit the text in them.

To play the game, start the slideshow.
If there is a corrrect answer guessed, click on the appropriate box to reveal that answer – complete with sound efffects!
For a wrong answer, click anywhere on the background.

Here is a link to the keynote template.

http://howto.dubbo.org/public/ff.zip

Here are the rules from wikipedia:

http://en.wikipedia.org/wiki/Family_feud#Rules_of_the_game

Let me know how it goes!