haven't read it. or seen it if it's a movie as well.
Pretty much a king of a country started using Soul Power to make his kingdom awesomesauce. It became awesomesauce, for awhile. Then contact with the kingdom ceased from the outside world, and a fog slowly moving across the land enveloped the kingdom (and other areas by time the game starts). No one who entered ever came out, so they couldn't ascertain what was goin on. Then (I think) Biorr of the Twin Fangs escapes the fog and tells the world what's goin on. What is going on is that soul-eating demons have ravaged the areas within the fog. Premuch everything has died, and what remains besides demons are soul craved men. The soul also acts as the mind in terms of sanity. The men who are left just mindlessly do whatever they did before the mist. So the soldiers defend the castle. Some miner people mine. Some tall people that died long ago have had their bodies reanimated. Patches the Hyena will make you want to kill him. You probably will. That's unrelated to what I was saying. You start off at this point.
The game is a solo/quasi-group game. You can summon other plays who have died in their game (and are thus (Blue) Phantoms) to help you in yours. You can have 2 with you at a time. Where you can do this is limited, though that is virtually nowhere. When the blue phantoms help kill a boss demon, they come back to life in their own word (you cannot summon others when you are dead).
PVP: When you are dead you can invade other people's games. you goal then is to kill the person's world you invading (they may have up to 2 other players with them). If you kill them, you rez back in your world. If you die, nothing happens (unless you die of stupidness, like falling down a chasm or from a trap). The PVP is pretty fun, of what little I've done. It gets your heart pumping and all until you get used to it. I'm still not used to it.
There's also World Tendency and Character Tendency.
Tendencies go from Purre Black to Pure White.
World Tendency being either pole opens up special events in each of the worlds (the world tendency is different for each world). World Tendency is determined by the collective actions of people playing the game online at the time. At black, the game is really flippin' hard. But you DO feel rewarded. At white, not so much (atleast for me anyway).
Char Tendency also affects stuff, but I'm tired of typing. Is now a greatest hits and so only $20.