[jacoblambda]

Subnautica has a somewhat related concept which is that at the end of the game you have the ability to send a single time capsule to the maps of new players. They contain text, a picture (taken with the in game camera), and a handful of items.

It's a cute little feature that allows you to send something helpful (or just amusing) to the next generation of players.

[lifefeed]

I got a little fish in my first capsule (along something useful that I can't remember, maybe a suit). I kept it the whole game, then passed it on in my own capsule. It's silly, but I still think about that fish.

[cbm-vic-20]

Sounds like a NetHack "bones level" that gets created when you die, and may appear in someone else's game. Full of cursed items, of course.

https://nethackwiki.com/wiki/Bones#Description

[IgorPartola]

Nothing like finding your own bones and being attacked by your ghost.