You know the ship of Theseus? The thought experiment where they keep replacing parts of the ship, until all the parts have been replaced. In a weird way, this relates to my D&D campaign. I've been running the game for over a year and a half, and it's been one of the best experiences of my life, but sometimes I wonder... Is it still the same ship?
When you play the same campaign for this long, life tends to get in the way. People graduate, get jobs, and sometimes move away. Old players leave, and new ones join in their place. Only one of the original four players still remains, but the campaign's continuity remains unbroken. My player count has grown to five, in fact.
I keep wondering what it's like joining in like this. For the newer players, the campaign I've run is just backstory – they never experienced it. I work hard to preserve the continuity, to make it seem like there's causality in play, but I don't know if I'm doing it just for myself, and that one player. I like to think it makes the game world seem more authentic. I may never find out if that's actually true.
In the end, it might not even matter. The newer players have already started their own continuity in the campaign. The torch has been passed, whether or not they are aware of it, and the ship forever remains a ship.