Hopscotch
Hopscotch is a classic child's game, not to mention it's free and easy. Kids use chalk to create a hopscotch board with alternating one and two box designs. Each player tosses a rock onto the board, hops out on one or two feet as directed by the number of boxes, picks up the rock, hops to the end of the board, turns around and hops back again. Any players that hop incorrectly, fall down or drop the object are out.
Paper Football
A wad of notebook paper, two players and a table are all you need to play an indoor game of paper football. Tightly wad a sheet of paper into a ball or football shape. One player stands at the end of the table with his wrists wresting on the surface, his thumbs touching and his forefingers pointing upward like a goal post. The second player places the ball on the table and flicks it toward the goal with his finger. Players switch after each turn and score one point for each goal. The first player to the pre-determined point mark wins the game.
Water Races
Cool off during a summer afternoon with an easy water relay-race. Split the family into two or more teams and select a clear area in the yard. Designate one end of the area as the start and one end as the finish. Supply two buckets, one at the start and one at the finish, for each team. Fill the starting buckets with water and hand each team a ladle. The first player on each team ladles water from the starting bucket, races to dump it in the finish bucket and races back to give a teammate the ladle. The first team to fill their finish bucket halfway full -- which can be previously marked with tape to avoid guessing -- wins the game.
Family Memory
Create your own question-and-answer memory game to keep kids entertained on a boring night. Each family member writes up to 12 questions on paper scraps. Questions can range from "Where did we spend X's 10th birthday?" to "What is Daddy's first name?" Questions are tossed into a bowl so that players may get their own, or somebody else's, questions. Players take turns picking a paper and answering the question. The player that gets the most correct answers wins the game.
Tag
An old-fashion game of Tag is an entertaining way for kids to work off energy. Any clear, level, outdoor area that works for running will work for the game. Players designate who's "It" and what object serves as a base. Players run around to avoid tagging (touching) by the "It" player, which means they're out of the game or automatically "It" instead. Assorted versions of the game include television tag, where players shout the name of a television show to automatically become "safe" and shark tag, where each tagged player adds to a growing pack of "It" players.