Communication is at the heart of community, both in practice and etymologically (meaning, they share the same root word, from the Latin communis, which I believe means common, or at least that's what I gather from my dictionary).
But, even a trivial amount of communication can lead to a community feeling, and thus I link for you this review of the game Journey at No High Scores.
There is also a button for speaking. Or singing. Or laughing. Or screaming. It’s your choice. The reason it’s there is because eventually, you will come across another pilgrim that will accompany you. It’s another player, although you don’t know who they really are. And you can’t speak to them except through this one button and what you do in the game.
On my journey, I went through an amazing range of emotions, many tied to my companion. When he (or she) would be away, I would feel sad and look for them, pressing the button to see if they’d respond. When they did, it was a huge relief. We worked on some of the game’s cryptic, simple puzzles together. We celebrated when we made it through an area. We laughed as we slid through the desert through crumbling gates left behind by unknown builders. We hid together from a giant dragon made of cloth.
But his scarf was longer than mine, and I wasn’t quite sure why. I wanted mine to be like his. When we were close, we replenished each other’s energy. I can’t help but think that maybe the other felt like they were taking care of me, sharing his wealth, knowledge, experience, and energy.
Eventually, at the very end, I lost my companion during a dizzyingly ecstatic sequence that’s best left for you to discover. Walking into the final section of the game, I was alone. I felt guilty about going on without my companion. Was I so caught up in my ecstasy that I neglected the person who walked with me all of this time? I stood on a cliff, pressing that button to see if they would answer back. They didn’t. I moved on.
I believe the button-press just makes your avatar "sing" a note, but I haven't played the game yet. You can probably find it in the videos at the Journey site.