Entertaining activities are the heart of any successful summer party, but adult guests require more sophisticated challenges than children's games offer. If the game is not challenging enough for the crowd, guests will become bored and disinterested in the activity. Planning more games than needed ensures you have something to replace any activities guests find dull.

A messy outdoor game of bocce will entertain adult guests. Bocce requires one small “target” ball and several large “tossing” balls. The small ball is thrown onto a flat surface, such as a lawn, and each player tries to toss his ball as close to the small one as possible. Egg bocce requires each guest to sign his eggs to personalize his “ball.” Each player takes a turn tossing a raw egg at the small target ball in an attempt to get the tossing ball close to the target without breaking the egg.

Plastic buckets, glasses and water are all you need to entertain party guests with a relay race. The game requires a starting line at one end of the yard and a line of buckets at the opposing end. A player on each relay team takes as big a drink of water as she can and quickly walks, without running, to the team’s bucket. Each player must spit the water into the bucket and race back to the team. The first team to fill a bucket wins the relay.

Though common for kid’s summer parties, a game of water balloon volleyball entertains and refreshes adults, too. A sheet draped over a clothesline or pieces of yarn secured across the playing area serve as a makeshift net for the game. Party guests split into two teams and follow basic volleyball rules, except that a water balloon serves as the ball. If the water balloon breaks on a team’s side, that team loses a point.

Small teams of guests work best for a relay race game. The game requires a starting line at one end of the lawn and a plastic bowl three to nine feet from the start. A player on each team places a cotton ball in the slingshot and tries to shoot the ball into the team’s bowl. If the player misses, he must run to the ball, grab it, put it into the bowl and dash back to the start. The first team to fill the bowl wins the game.

Adult couples will appreciate being entertained with a summer twist on a classic contest. Each couple uses basic pumpkin carving tools to turn a large watermelon into a carved piece of art within a specific time. Guests votes on which watermelon comes in first, second and third in the contest.