Also some of the best parts of Last Saints Row were the Boss presented LARP weapons and running around a LARP with them. (More than one LARP, even, with the DLC, clearly the developers had fun with it.) None of the GTA-style shooter mechanics were actually changed but a "wink-nudge" was added that the LARP players were very good at death acting. Also you could carry the LARP weapons the rest of the game and get silly nerf dart sound and visual effects everywhere else, which was silly fun in its own way.
ETA: Also not directly a LARP but a similar premise is the pair of Costume Quest games of kids running around doing Action RPG things to save the town in Halloween costumes playing well with that boundary space of what is real for them and what is heightened fantasy.
ETA: Also not directly a LARP but a similar premise is the pair of Costume Quest games of kids running around doing Action RPG things to save the town in Halloween costumes playing well with that boundary space of what is real for them and what is heightened fantasy.