Icewind Dale II is a wonderfully made sequel to Icewind Dale.
As with it's predecessor it is set in the wintry lands of the Icewind Dale and is generally focused on the doings of your adventurers.
Like the Baldur's Gate games and the original Icewind Dale the game involves strategic thinking (what spells to cast, who to attack etc.) and you might want to save it regularly because Icewind Dale II is a bit harder.
Multi-player is the same as Icewind Dale and Baldur's Gate, just have a disk for each PC you're going to be playing it on and connect the PCs.
This game deserves the 10/10 i'm giving it and is one of the best RPGs ever made.