[SixOfSpades]

One of the reasons that Baldur's Gate kicks butt is its replayability. Some games (say, for example, WarCraft) are extremely limited in this factor: Beat the Human campaign once, and there's no point in playing it ever again, all your games will be exactly the same. So then you beat the Orc campaign, and get the same result--now there's nothing left but the Custom Scenarios. But with BG, you could beat the game as a Chaotic Good Fighter specializing in Longswords and Maces, and get a completely different experience every time you play a different class, kit, alignment, favored weapon selection, party makeup, order of quests, etc. It's that replay factor that keeps BG2 a popular game even after--what--six years? There's always something that you haven't done yet, something for you to try next game. Take the Stronghold quests--have you been a Bard yet? what about a Druid?

There's always something that you haven't done yet, something for you to try next game. In this case, one of those somethings should be the Planar Sphere.