Capture the Flag
Divide into teams. Each team has their own area of a field that is considered theirs, and a flag. The goal is to capture the flag of the other team. However, once a player crosses into the territory of the other team they can be captured by being touched. When they are captured, they are put in a small area predesignated as that team's jail. Players can be freed from jail by one of their teammates making it into the jail area and yelling "free." To keep everyone safe, don't set up a crazy playing field that could cause injuries, play in the daytime, keep things under control and just have fun.
The Blob
Start the game with one person as the Blob. Like tag, that person tries to touch another. The difference is, once the Blob touches someone they have to become part of the Blob by holding hands. The first holds the hand of the Blob, the second holds the hand of the first touched, and so on. Pretty soon you'll have a long line of players glued to the Blob, trying to reach the few players still free. The more players, the better.
Sponge Toss
It's a hot day and you want to have some fun outside. The perfect game is a sponge toss. Pair up players. Put players in two lines facing each other two feet apart from one another. Give each member of one line a soaking wet sponge. The player has to toss the sponge to his partner two feet away in the other line. Every time the sponge is sucessfully caught, players take one step backward. The toss and catch is repeated until one player drops the sponge. That pair is then out. Continue playing until you have a winner. Players will get wet and have fun at the same time.
Balloon Stomp
For this game you'll need one balloon, blown up tight so it pops easily, and one long piece of string for each player. Tie the balloon to the string and the string to the ankle of the player. Make sure string is long enough that feet aren't being stomped instead of balloons. The goal is to bust the balloons of all the other players while keeping your own balloon safe. This is fun to play in teams to see what team is left at the end of the game or play as individuals. Be prepared for some balloons to come off of the string and some strings to come off ankles of players. Have another balloon and string ready to replace quickly. Play until last balloon is left unpopped.