Not an uncommon phenomenon by any means - and not surprising given the physical and emotional intensity of many LARP games.
In our circles it's referred to as Event Crash, and a number of the coping strategies here are familiar - particularly coming together later and telling stories about the event, both as a way to froth excitedly at people who have the context needed to understand the excitement, and as a way to contextualise the event's experience with others who were there.
The emotional impact that highly immersive games can have can't be underestimated, and any mechanism by which a medium can affect its participants so profoundly is certainly worthy of attention and further study.
Live-action role-playing (larp) occupies a unique place among analog games, for it demands as much from players’ bodies as it does from their minds. It comes then as no surprise that many players find themselves in the situation of feeling confused, exhausted, and emotionally raw after a larp event.1 In fact, larpers frequently exhaust themselves in advance through the leisure labor of planning their costumes, character actions, possible outcomes, and interactions. Subsequently, the event itself often features what some would describe as “intense content” – dramatic interpersonal dynamics, improvisational comedy, combat, political struggles, problem solving, etc. Intense content is there by design in order to maximize the emotional impact of the game. The sheer amount of emotional intensity experienced in a short time frame can impact any given larper, regardless of whether or not they found the experience enjoyable.