Kangaxx was perfect in that he was brutally hard, but you weren't forced down some linear path of things you HAD to do in order to defeat him. I read or saw many ways people killed him back when I still played it.
What are you talking about? The summoning of Kangaxx is a very linear quest path, as you have to gather his remains first, from various tombs in Athkatla. That being said, I loved the Kangaxx fight initially. Of course, now I know some serious cheese-tactics to kill him. Did I ever mention how much I love my Rings of the Ram?
A much more always-interesting fight is the Twisted Rune pre-Underdark.

Well, since I played a mage conjuror (back then it meant you get extra spell slots at the cost of not being able to use charm spells - who needs charm spells when you can melt their heads off? They changed that in later games) I used to walk into every BGII battle so laden with protective spells, I once soloed a lich in the Underdark. Not Kangaxx though. But BGII made playing mages real interesting, it had what, over 120 spells to choose from?
In contrast to the NWN games, I actually found all the classes diverse and interesting (rather than pushing for the next PRC, going through 3-or-so levels at a time before anything happened with any base class.. at a time).
One of my absolute favourite runs was a multiplayer run where I made 2 characters, intended to be twins; A elven Kensai and a elven Archer. Remember that this was back when elves had extra attacks with Longbows and Longswords. By ToB and with Improved Haste, that equated almost the full 10 possible attacks/round.
