The Last game I played was Splatoon 3. It really depends on a few things, Am I an Inkling/Octoling? Do I speak the language? Where am I? In Splatoon lore all humans died in mass floods, so if I was still human I would probably be studied. Also, if I’m in the middle of the ocean I would be screwed either way. Assuming that I am in a major city or at least near civilization, and I am an Inkling/Octoling, and I speak the language, I would be fine. As for what I would do, I would sign up to work at Grizco, and once I have enough money buy a gun and participate in turf wars to gain money, eventually buying an appartment.
Fallout London. It’d be an intense half an hour trying to open inaccessible doors before I’d crash back to safety.