We just had a preteen event last month called Nerf Wars. It was a total hit and can be played with a handful of preteens or hundred.  Great relational, fun night. And very simple. Here’s the skinny:

Big room. Everyone has a nerf gun with darts.  Two teams who line up at opposing sides of the room.  All out war.  If a player is shot, he/she is frozen untill another teammate tags him/her, which sets the player free.  Have leaders get a general sense of what team is getting tagged the most during game time to decide the winner. Or call time after each round and count the number of players frozen at the time. Whichever team has the most frozen is the losing team for that round.  Teams can go over to the opposing team’s side at any time.  Provide nerf guns and ammo for players, but announce they can bring their own gun if they wish.  We had a 5th grader pick up a $50 automatic nerf gun and 150 ammo darts on the way to the event.

Spice it up a bit and buy some laser lights, turn off the lights and play some techno music for a few rounds.  Really adds a cool effect.

Also, go to $1 store and get some cheap sunglasses for all to wear (for protection but keeps the cool factor).

We charged $6 per person, which covers most of the expense of the event. The rest came out of budgeted money that we have designated for these type events.

Our preteens had a total blast.  I did too.  Really fun to shoot the preteens in my group with nerf darts for over an hour!