Like Demon's Souls, Dark Souls possesses a number of incredible online features that make you feel like one node on a giant web of identical worlds. You see the ghosts of other players on your travels, and they are less transparent the closer you are to a bonfire. These players don't exist in your world, but are more like echoes from a parallel kingdom that resonate with your own. You also encounter bloodstains that mark the deaths of other players; by activating one, you watch the player's ghost reenact the final seconds before death. These aren't just neat features that impart a sense of community, though they certainly do that. They also let players serve as silent, inadvertent guides to each other. By both living and dying, you might be another's quiet savior. It makes Dark Souls an unusual and wonderful contradiction: you feel remarkably alone in this frightening place, yet simultaneously part of a large multiverse where simply playing the game makes you part of a chorus of silent voices urging each other forward.
You can offer more direct assistance by creating helpful messages from a series of canned words and phrases and leaving them for other players to read, and you can heed advice others leave for you. And if you need extra help, you can summon a stranger to your world, or be summoned to another. Tackling a boss with one or three other players is a lot of fun, though there are other ways of assisting your fellow travelers. One way is to drop an item; left long enough, it will transform into a phantom and wander into someone else's game. Such phantoms leave behind precious items, though they must be vanquished before you can reap your reward. Of course, you might prefer antagonizing other players rather than assisting them. In that case, you can invade them as a black phantom. Just like in Demon's Souls, being invaded exponentially increases your tension level, because you have to worry not only about standard creatures, but also about another player hunting you down.
Dark Souls shares many attributes with Demon's Souls, yet possesses enough distinct facets to feel fresh and exciting even to veterans of the older game. One of those distinctions is an uncommon currency called humanity. Your basic form is that of a hollowed soul--that is, undead. In this state, you can't summon others to your side or invade their worlds. Doing so requires you to possess humanity. Humanity has benefits beyond allowing you to summon and, like souls, can be retrieved after death if you return to your bloodstain. It can also be sacrificed at bonfires to increase the number of health flasks you receive when resting, which can be a real boon. But being human makes you vulnerable, because it opens you to invasions. Other players don't steal into your world just for the fun of it; they want your valuable humanity. The good news is that if you defeat your pesky invader, you receive his humanity for your troubles.
Covenants are another element unique to Dark Souls. These are like factions, and joining one offers distinct benefits, not just for you, but possibly for other players. Finding covenant leaders isn't always straightforward. One is a cat lounging in a window, and it's easy to miss as you rush past, trying to lose the soldier dogging you. Another is a demonic monstrosity lurking behind a hidden wall you might have walked past a dozen times or more. Joining that cat's ranks has a great benefit: you can walk peacefully among the wolves and ghostly figures of the forest. That hidden demon has powerful pyromancy spells to grant you, among other choice offerings. Furthermore, players in the same covenant share certain benefits. For instance, comrades might enjoy the effects of a miracle you cast. Which covenant you find most appealing depends on what you want to get out of the experience; some benefit player-versus-player fanatics, while others are more appealing to sorcerers than to thieves. The game isn't always clear about the risks and rewards various covenants offer, but unraveling these secrets is one of Dark Souls' cerebral delights. Not sure what donating humanity to your faction leader might accomplish? Do it and find out for yourself. But be careful, because betraying a faction has consequences, and forgiveness isn't something you can pray for: it must be bought, and it doesn't come cheap.
Covenants aren't Dark Souls' only source of mystery. You experience events that you couldn't have seen coming but that still make a kind of demented sense when they occur. Touching a glowing ring after defeating yet another skyscraping boss initiates a memorable voyage. A creature appears where none was before, eager to exchange unused equipment for a few souls in return. You also encounter strange characters locked in cells and trapped in golems. Should you rescue those imprisoned individuals, they may appear later in Firelink Shrine with words of advice, gestures to teach you, and new spells to purchase. Others may not be what they seem, and if you have reason not to trust them, you can drive a sword into their flesh. Doing so may grant you a helpful ring or piece of armor, but you might lose certain benefits by denying yourself future access to these folk.
Not all unexpected circumstances are pleasant ones, however. Falling victim to a curse halves your health bar, and curing it requires purchasing a special stone--or sprinting through haunted ruins, where a special healer offers his services. Idle long enough near a disgusting, larvae-filled foe, and it might infest you, turning your head into a giant egg that eats half of the souls you earn. Finding the right cure for your head tumor is a quest of its own, though it isn't one granted by an NPC, but one born of circumstance. Such occurrences might seem harsh, but they're actually a sly method of making the adventure feel like one of your own making, rather than one governed by a structured quest log.
Dark Souls requires intense focus. This isn't a lighthearted romp in a bright and colorful fantasy world; it's a methodical journey into the frightening unknown. And that's what makes it so riveting. Some games try to scare you with bump-in-the-night shocks and far-off howls, but Dark Souls doesn't require such predictable methods of terror. Its terrors emanate from its very core, each step bringing you closer to another inevitable death. How amazing that such a terrible place could be so inviting. The game's world is so memorable, and its action so thrilling, that it might invade your thoughts even when you aren't playing, silently urging you to escape the real world and return to this far more treacherous one. Dark Souls doesn't just surpass other dungeon crawlers; it skewers them with a razor-sharp halberd and leaves behind their soulless corpses.