I have run many larps for kids, typically in the 7 to 10 year age group.
The main thing is to Keep It Simple. All kids instinctively know how to use a sword (or other larp weapon), so I reckon what you need to do is provide character classes that shine in different ways.
Assume you have a rule in which if you get to 0 HP you are incapacitated, so must lie on the ground (this allows Healers to figure you who to heal).
You only need 4 classes:
- Fighter - can use shields
- Mage- can use simple spells such as Magic Missile (throw a spell packet, 3 HP damage), Wall of Flame (2 mages holding a rope between them, 3 damage if touch and the mages can maneuver the wall), Shadow Self (Mage gets to run into the fray and do as much damage as they can, but after 2 hits their Shadow Self is gone, and the Mage returns to where they start, having taken no damage)
- Healer - Can heal others (this is a good non-combat character)
- Rogue - Can hide next to any large tree/shrub by putting their hands on their heads. The encounter for this class is some kind of guarded artifact that either the guards at too powerful or you can’t afford to let anyone know that the artifact has been stolen. Have one artifact per Rogue and send them in. The guards should make a big deal about “hearing” the rogues sneak through the forest, but whenever they look over at the rogues, the rogues are using their power to be hidden. It works really well if the guards talk about it amongst themselves and one says (pointing at a rogue) “I heard something over here!” and the other says “You’re dreaming! Stop wasting time !” The rogues to the feeling of danger, but ultimately get the job done, while all the other PCs wait and hope.
What we did was have a totally linear plot arc.
- Start here (typically the entrance to the park).
- The SItuation: an NPC who explains the Danger and What Needs To Be Done, and also Why The Adults Can’t Do It (i.e. it’s up to the kids, and only the kids)
3, The Encounter (not far along the path) with a Major NPC (lots of talking, perhaps some challenges for the kids in the vein of “solve this riddle” or "do this cool thing right here (such as a specific shape with their arms) etc.
- They get told how to get to the next Encounter (which will assist in The Quest)
- Somewhere along the path, are attacked by the Bad Person’s Hench-People (and the kids always win, especially when it looks most desperate!)
Repeat 3,4,5 until they get to the Finale
The Finale is basically a Boss Level. At this point, the kids should have everything they need to defeat the Boss, and it’s a matter of fighting their way to the centre of the Boss zone and then Implementing The Mechanism (a ritual, putting the Artifact In The RIght Place, whatever).
I must stress that the kids always win, and the job of the adults is to provide tension and challenge only.