Story+Stuff: You are already dead. Well, undead at least. Your character has become an outcast from society, banished to a pretty horrible place for bearing a curse that continually revives him or her, but takes away a bit of humanity each time. The story is presumably about your character dealing with this exile while attempting to improve their situation in some way.
The whole game will positively EXUDE atmosphere, with lots of beautiful and/or haunting scenery, excellent sound effects and ambience, and a minimalist soundtrack.
Gameplay. An open-world dungeon crawler of sorts. The world is made up of interconnected themed levels, each with a few bosses, lots of smaller enemies, a few storyline/merchant NPCs, various hidden items, and a sprinkling of campfires that act as respawn points and refill your stock of healing items. On any given level, you'll be exploring twisting passages, making inroads into more difficult areas, and devising a plan on how to hunt down the boss.
Combat is pretty intuitive, with two shoulder buttons assigned to the item held in each hand, in addition to spells and consumable items. There's a lock-on system akin to Zelda, but manually adjusting the camera works just as well. The fights themselves are a little on the slow side, but there's a lot of emphasis on timing, and exploiting enemies' weaknesses while minimizing your own. It's not about trial and error per se, but you do need to be attentive and actively working to figure out all the little subtleties of the mechanics and levels so you can use them to your advantage.
Multiplayer: In a sense, it's a massively multiplayer offline RPG. You can leave notes in the levels to warn other players of traps, make silly comments about the level or enemies, or for no reason at all. Whenever someone approves of a message you left, the game rewards you. Places where players have died show up as bloodstains, and touching them let's you watch a brief replay of what happened to them. This is also quite helpful.
On the "live" end of things, other players can enter your game as phantoms, either to help you, or kill you for their own benefit. How exactly this is done has not been mentioned, but it will most likely bring in random players, rather than letting you grab people from your friend list. (Also, there's no in-game voice chat because the developers think that would spoil the mood.) Whether players are hostile or friendly to you will depend on the storyline decisions you make, such as aligning with a particular faction. In addition, you'll be able to affect other players' games by leaving signs in their game worlds that have positive or negative effects, and may serve as a back door to those players jumping into your game as well.
Comparing Dark/Demon's Souls to other games is hard. They're most closely related to the King's Field series, which also had a rather unique niche.
