Both intimate and lonely, the world is littered with signs of other souls like yourself, shadows of people playing online. They leave messages for you to read, and when another player is exploring the same part of a level as you, they can be seen briefly wandering around as a white ghost. Some players can be summoned to help, and some will invade to try and take your own soul.
More often than not, though, all you'll see of them is their white shadow lumbering through the very same terrain you are, lingering for a few moments only to disappear into thin air. -