As a change from running a Treasure Hunt - here is a great childrens game. Follow the links for other party games to entertain your kids:

Match It

This is an excellent ice breaker type of game, as it requires quite a lot of searching to find your match.

Prepare by acquiring a piece of cardboard for each two guests. Cut the card in two using a unique and irregular pattern for each piece. Something like a jigsaw puzzle. Shuffle the cards.

As your guests arrive, give each child a card. They must then attempt to find their matching half. Pairs that have successfully matched can be given a small reward.