This is the most well-known game of all time. Choose a "hider". While the rest of the players count to 20, the "hider" find a good hiding spot in a closet, under a table etc. Then the group goes looking for them. The player who finds the "hider" gets to be the next "hider". For little ones, try having the "hider" make bird calls or other non-verbal noises. Also see Flashlight Hide and Seek.