Dark Souls II - Preview @ Gameranx
In World of Warcraft and other RPGs, being dead means being unable to interact with the world, with a one way ticket back to your corpse and back to the land of the living. It goes without saying that in most games, giving up your humanity in order to wander throughout the world as an undead being is the equivalent of a game over state.
This is not the case with Dark Souls, where being bereft of your humanity is the only way to ensure you aren't invaded by other players. You see, players can't invade your world while you're undead so short of disconnecting your PS3 from the internet, being undead isn't a bad way to be. This is changing in Dark Souls 2, a game with far more emphasis on multiplayer interaction.
As a bonus Joystiq also has a small article about the game keeping Havok physics.
Information aboutDark Souls II
SP/MP: Single + MP