How the stones tell of the ones who fell

This is a legacy tabletop roleplaying game about death and what you live behind. In the secret world, you live only for ten years after your fall. There will never be anyone else from the upside, other than you and your companions, during your remaining lifetime. The only thing you can do is leave marks behind. When your favorite necklace breaks, it sings a sad song, echoing forever in the wind. When your best friend dies, you leave a letter to them buried beneath a rock. Three sessions from now, another group of characters - maybe, probably played by another group of players, find that letter...