I just wanted to add that I agree with all of this and was also imagining a LARP option, especially because I live in an area where I have access to a subway system pretty easily! I feel like the hardest part would be communicating with each other, and also the fact that if you were to base it in a real subway system, it'd be hard to manage other people being present. I almost was imagining more of like... an immersive solo-esque experience.