Capture the Flag
This is a classic game that only requires two handkerchiefs or T-shirts of different colors.
Divide the yard or outdoor area into two separate spaces and divide the kids into two groups. Designate each team to a side, and give each team a handkerchief. The teams pick a spot as their home base and hide the "flag" around that area. Each team tries to capture the flag of the other team and get it back to their own home base, to win the game. The teams must determine how to find the opposing team's flag, while also guarding their own. Make things harder by letting the teams tag players from the opposing team to eliminate them from the game.
Outdoor Scavenger Hunt
Create a list of items found in the great outdoors. For example, include a four-leaf clover, certain colors of flowers, leaves, and rocks.
Divide the teens into groups and give each group a list of the items. The first team that makes it back with every item on the list wins. Alternatively, give the teens just an hour and reward the team that finds the most items and makes it back within the hour.
Murder Mystery Wink
Cut small slips of paper and write 'townsperson' on each slip, except for one. Write 'murderer' on that piece of paper. Let each teen select a slip of paper, then you can start the game.
The 'murderer' must kill others in the group by winking at them; once the 'murderer' winks at a player, that person is out of the game. In the meantime, the other players wander around the outdoor area, watching the others, trying to determine the 'murderer.' The winner is the person who correctly identifies the 'murderer,' or the player who 'murders' all the others.