Ok excuse me for posting about a "mostly" single player game but this game deserves notice. Why? Because its elaborate, well-written, complex, and funny. Not only that the battle situations are all fairly unique and offer significant room for creative utilization of classes and skills to almost no restriction. Want to beat the game with just one guy of any class? Go for it. Want to do it with all rogues? Fine. There will be certain rare things you can and can't do but most of it you can and even the challenging things you can usually do. The only thing you absolutely have to have a party for is a demi-lich, though you can summon Valhalla warriors to get imprisoned for you if you want also. If you're clever with traps and you're a bounty hunter you migth even be able to kill a dragon alone. (Or if you are a powerful mage, magic missile is bad news bears once you lower their magic resistance) (And there's only two demi lich's in the game and they are both optional though one is definitely worth assembling and killing for his super powerful ring of regeneration)
Baldur's Gate 2 shows what happens when fun and the player experience and plot are put at priority 1 instead of budget and so on by a large experienced company (Black Isle/Obsidian now)
The game is rife with npc's who have more fun, character, sass, intelligence, interaction, and endings, than any lukewarm bioware game that has been released since. You can play the game as Good, Chaotic Neutral, or Super Evil and have a TOTALLY different experience. If you are super evil then the law comes after you constantly and they mean business but killing them gets you even more exp and powerful items. Reputation is hard to make go up but easy easy to make go down. Just start killing civilians, its as simple as that. Neutral results in a unique game also as the neutral characters like you more, and it has its own unique romance and plot line. I haven't yet experimented with that one to the full degree but I've beaten the game on evil and good and I of course like good better but I respect how much detail and care went into the evil line, since it is counter to your usual half baked stuff, much better than KOTOR 2's lousy evil ending. Actually KOTOR just made we wish Black Isle had never been broken into two companies. It lacked a certain something but it attempted many good things.
Anyways back to Baldur's gate 2. So The graphics aren't totally amazing but they aren't that bad either. You can control a party of 6, there IS collision detection and you can set up barricades to protect your more vulnerable friends. You can actually make friends or enemies with your subordinates, and they might go nuts or do other things if they make friends within the group and that other person dies or you insult that person or whatever. Drama drama, but it makes for a rich, more realistic experience never again even attempted by any company to this level. Area's change based on what you accomplish, stuff happens. Sometimes good, sometimes bad, your lover can get turned to stone, turned into a vampire, marry you, have a kid, or get blown into chunky kiblits by a fatty Shadow Dragon unless you hide in a cloud of obscurity produced by a magic stone.
My favorite place might have been Underdark or Watcher's Keep with all its puzzles and deadly deadly battles, but its hard to pin it down, Illithids were definitely my least favorite enemies as they had a chance to kill you instantly by sucking out your brains. Not a game for wimps. Definitely a game for you if you like challenge and plot. Can be played with friends online via Gamespy's service just fine.