Thirteen is the magical number that places your child firmly in the teenager camp. At this age, many boys have begun to narrow their group of friends to the guys who will stand by their side though the rest of their teen years. Parties get smaller, and balloons and streamers won't cut it anymore. He may also want to invite over a few girls, so incorporate gender-neutral ideas if needed.
Host a murder mystery based on the game Clue. Make signs beforehand to hang on the doors of the rooms. Label them with the room names from the board game, such as the drawing room, or come up with your own names for each room.
When the kids arrive, escort them to the dining room for tea, soda and snacks. Serve all of the food on fancy plates to match the sophisticated mood of the party. Have each guest draw a slip of paper from a hat. They aren't allowed to show it to anyone else. Have their party persona written on the slips, such as rich doctor, retired professor and so forth. One slip will be labeled as murderer along with the persona. The kids act out their new personas, except for the murderer, who must try to make everyone think he is innocent.
When they are done eating, have another adult scream from another room. When the kids rush in, they will find the adult dead. Decide before the party how much information you will share with the partygoers, such as the murder weapon and backstory of the victim. Hand out notebooks for the kids to write down their clues, and let everyone spread out to try to solve the mystery.
Hide clues around the house for the kids to find. The clues should subtly begin to point toward the murderer's persona. The child that figures it out gets a special prize.
Combine this party with a sleepover for the biggest impact. Set up your den for the perfect movie night. Lower the lights or replace them with blue- or green-colored bulbs to set the mood. Move furniture so there is plenty of room to spread out sleeping bags. Use the coffee table or another low table to hold a large array of snacks. Popcorn, chips and other finger foods are perfect for the movies.
Pick a theme for the movies you'll be showing. Scary movies, teen comedies or action adventure are popular genres for 13-year-olds. Adults should stay out of the room except when refilling snacks and drinks--boys this age don't desire or require a lot of supervision. Let the boys stay up as late as they want watching movies, and have a big breakfast ready for them in the morning.
Purchase a roll of raffle tickets from an office-supply store or make your own. Hand out the tickets to the boys as their movie ticket when they arrive. In the morning, raffle off the DVDs they watched as prizes.