This is again an autonym. The "Nordic" part is more about origins and mass of the player base than a true regional limitation of any sort. The "Larp" designation is part of the name for reasons that are unclear to me, even tho' its ideas started in tabletop roleplaying, and its philosophy and aspirations are realisable in tabletop games just as much as in dress-up games. (Edit: Spelling it as if it wasn't an acronym is a shibboleth of Nordic Larp, so in keeping with the autonym principle I've edited it to follow that convention when referring to the culture, but kept the activity as LARP)
Nordic Larp is built around the idea that the primary goal of a roleplaying game is immersion in an experience. Usually in a specific character's experiences, but sometimes in another kind of experience where player and character are not sharply distinguished - the experimental Jeep group often uses abstract games to affect the player directly. The more
"bleed" you can create between a player and the role they occupy within the game, the better. Nordic Larps often feature quite long "sessions" (like weekend excursions) followed by long debriefs in which one processes the experiences one had as the character.
Embedding the player's character within a larger story can be one way of producing vivid, absorbing experiences, but it's not necessary and may even interfere with pulling it off (especially when done badly). Nordic Larp players emphasise their collaborative aspects, but when you drill into this, it's a rejection of trad's idea of a single DM-auteur crafting an experience, and the collaboration is there in service of improving immersion by blending player and character agency more thoroughly.
I think LARP conjures up images of people doing fantasy cosplay, and there are sometimes elements of that in some Nordic Larps, but I actually think the trend has been away from fantastical games to scenarios and set-ups that are closer to real life since it allows the incorporation of modern architecture, technology, and other details from the real world to facilitate immersion.
Nordic Larp's first major publication that I know of is the very self-conscious
Manifesto of the Turku School by Mike Pohjola in 2000, and I think the early community is in dialogue with the Forge crew, tho' the two groups have very different ideals of play. By 2005 you have specific groups like
Jeep developing these ideas, and in 2010 you get the publication of the
Nordic Larp book. Nowadays there's also
a wiki and
an official website.
Nordic Larp is the part of roleplaying that seems to receive the most grants and funding for academic study. I'm never sure why, tho' I suspect some of it has to do with the interest in commodifying LARP ideas to create immersive entertainment experiences for tourists at mega-resorts in the
Gulf Cooperation Council countries. I'm not going to link to any specific individuals connected to Nordic Larp who have jobs there to avoid doxing private individuals, but they exist (please don't dox anyone in the comments, either).