On the topic of video games which offer unexpected connections with other players (such as Journey), I finally remembered another example I was thinking of: The First Tree. I was moved by a message I found carved into the tree at the end of the game, and I was surprised when it asked me for my own message - and only afterward did I realize I had seen someone else's words, and had carved my own for someone else to find.

This person's art is wonderful, and has some great messages. https://www.thelatestkate.art/