Today, Atlus and Sony announced that the online servers for Demon's Souls will finally be coming to an end. It's a long overdue closure after the servers were originally meant to shutter back in 2012. Come February, what I believe is one of the greatest online systems in any game will finally shut down, so it's a good time to mourn and appreciate everything Demon's Souls' online servers did for those of us who have died in its online world.
Off the top of my head, I can't think of any other hybrid online multiplayer system that blends passive and active multiplayer gameplay like the one Demon's Souls pioneered for From Software's Souls series of games. Even if it isn't the first system to do what it did, the online system in Demon's Souls is damn near perfect in my mind. It separates Demon's Souls from other competitive online experiences by transforming the game into something like an online ghost story.
Playing online in Demon's Souls instates a few things. One, it means that you can see the ghosts of other players as they re-enact their last moments in any given area. Seeing the replays of other players' death is helpful in navigating the dangerous world yourself, avoiding traps you might otherwise fall for.
Two, it also allows you to read and leave messages for other players. It's a more direct approach that lets you warn other players of impending doom, or trick them to their deaths. In Demon's Souls, you learn that ghosts are pretty fickle—and so are other players.
Lastly, it means that other players from other worlds can be summoned into your world to either assist you, or murder you. Other players can become yet another enemy in a game full of already difficult challenges, or the extra help you need in particularly difficult trials.
Overall, the online system in Demon's Souls is a thing of beauty. One that blends into the main campaign without feeling tacked on. It was a breathing system that helped make a game about dead souls feel alive. Other players served as guides, vengeful spirits, tricksters, and visions of fortune or peril. All of it lending to the ephemeral feel of Demon's Souls that later Souls games haven't been able to re-create.
In Demon's Souls, the kingdom of Boletaria is invaded by colorless fog that killed the live inhabitants of the world and ushered in a wave of demons. Players are one of many knights tasked with saving the kingdom, knowing they'll live or die and live and die again to succeed to this end. While Dark Souls and Bloodborne also utilized the same online systems as Demon's Souls, the story of other souls crossing over boundaries into your world—or vice versa—is more resonant in Demon's Souls where players are literal spirits rather than undead corpses.
It was also goddamn terrifying.
If you've ever encountered the words, "____-player has invaded" you'll know the panic that sets in when you know a live player is now an enemy in your already difficult game. The online functionality also helps create new, emergent gameplay elements where certain areas (like Shrine of Storms) become de facto PvP worlds where players can test their mettle against one another. It was even used in an ingenious boss fight against a demon called the Old Monk who is, in fact, another live player summoned to role-play as the enemy boss.
Shutting down the online servers for Demon's Souls means losing all of these things that helped make the game special. With no private servers available, Demon's Souls' online functionality is pretty much gone forever, and every subsequent playthrough will lose these key features. The online mode in Demon's Souls is core to the game in a way that enhances the overall storytelling and world, instead of just beefing up a product as just another feature.
In a way this permanent end is kind of appropriate for the game. Demon's Souls will never be the same once the online servers go down, but that's just the risk with old ghost stories. Eventually you forget some detail that ends up changing how the story is told.