How about a new festival that involves children's games? Each game would be a timed event and available a few times per day. The top 3 winners of each game would get certificates they can turn in or gain unique prizes. So there could be a hopscotch competition, 4 squares, etc. And then there could be a big event such as tag where all participants have to avoid a small group of NPCs that are "it" for a certain amount of time. You would have the entire city to run around and avoid contact but could not enter your home or guild or use any speed buffs or mounts. Rewards would be based on how long you were able to survive the game.