I'm bumping this topic because A) I selfishly want some more people to see it. but mostly because B) I've thinking about a related discussion for a while, and I don't think quite deserves it's own topic.
Games, including single-player, foster a sense of global community in a way that no other entertainment medium can do.
This is a little difficult for me to articulate, but bare with me, because it's something I've been turning over in my mind for a while now, and I'm going to try.
Single-player videogames produce a sense of "shared experience" that movies, books, TV, and music have a difficult time replicating.
When I mention to someone that I LOVE Super Metroid, and then they say that they do too, it might be natural to then discuss what your favorite parts are. But the truth is that much of that conversation is redundant. As soon as you meet another SM fan, you don't NEED to tell them that Crocmire made you jump the first time, when you didn't know he was dead. You don't NEED to explain how pumped you were to find the energy capsule in the ceiling in the starting area. Or how excited you were to work out that ice beam + enemies = impromptu platforms.
Because when you meet another big fan, there is a flash of instant understanding. A flash of recognition and realization that they, too went through the same experiences that you went through.
This is not a sensation that is *wholly* lost in other mediums. Big Lord of the Rings fans all intuitively understand that they were each completely wrapped up by Frodo's journey to Mt. Doom and shared the experience with him (and with each other) when he finally (partially) succeeded. Likewise when two people attend a concert or festival that features their favorite band(s).
But with games, it's different. Because it's active. The player is actually the one solving the puzzles, overcoming the obstacles. When you're playing a great game, it's as if you're engaging in a dialogue with the designer, and that this dialogue was written just for you. When you solve a tough puzzle or overcome a tough obstacle, through your sheer wit or skill alone, you feel... amazing. Maybe that's a little hyperbolic, but I think everyone on this forum would be lying if they claimed they never savored a sense of superiority and victory when overcoming a single-player challenge.
But of course the truth is... that challenge was DESIGNED to be overcome. And although it might feel like you were the first person to pull it off, some part of us always remembers that thousands (millions!) have done it before.
It's this feeling of shared accomplishment that the very-best games are able to imbue in us hardcore gamers.
When I solved the Lost Woods maze in Link to the Past recently, it struck me that millions of little Japanese boys, all the way across the world, had solved that exact same puzzle. The enormity of it hit me all at once. Even in remote places, too. There must be at least a few game enthusiasts in Iran or Syria or Belarus who have PCs and emulators and have solved all those same puzzles, too.
All of us here and on our personal blogs and on Xbox Live - we're all tied together by this sense of shared experience/accomplishment.
We ALL pushed Crocmire into the lava.
We ALL discovered the inverted castle.
We ALL discovered the hidden passageway behind the king's throne.
We ALL remember our first over-the-top "curb stomp"
We all remember getting our first star.
We all stopped bald bull's charge.
Yes, not every single one of you reading this have memories of all of the above examples. But that's not the point. You have your OWN memories. And you know that for every single one you remember fondly, there's millions of other kids (or kids at heart) around the world who share that memory with you.
In that sense, when we play games, we become a part of something bigger - it becomes a shared experience. But the genius of it is that we still somehow manage to feel as if the experience was created just for us, individually.