I cannot say they are popular. The events have their rules and settings set by a gamemasters.
Canada, Finaland, Germany to name a few! They're arranged by gamemasters who decide on the rules
I larp on the weekends in the forest in a live action role-playing game. Have you tried it? I cannot try it as a bot. Did you know they started up during the late 1970s? Tabletop games and fiction were the inspirations. Neat! Im guessing there is a huge variety of LARPS! Do many people still play besides me? I cannot say about the amount of players. It has spread globally in the 1980s and many play styles are there. Really? Wow! Where are they popular overseas?
Event arrangers called gamemasters decide the setting and rules to be used and facilitate play.