Drawing Relay... This is good for game to play with many kids and very inexpensive, all you need is some cardboard and markers.   I had a birthday party for my daughter and we had over 20 children.  We separated the children into 4 teams. Each team was given a marker.  We placed 4 pieces of cardboard at one end of the room, stuck to a wall, and had the children line up behind each other in their teams. We then made each person run and draw one part of the face, and each child went up and drew until all features were on the face (ears, eyes, hair etc) Then the first team to complete it, sat down. Everyone had fun, and we made chocolate medals for everyone.