3rd Edition Rules. The ruleset BG2 uses is a hopeless scramble of 2nd and 3rd edition, and in some places makes no sense at all. Also, I believe it will use the IWD2 spells as well, which is neat as well, and gets rid of that thrice-damned imprisonment. More than anything else, however, it gives us a chance to play BG in a completely new way. No uber-godly HLA's that turn a thief into a claymore-wielding dervish, or let a mage nuke an entire battlefield. Feats will make saves harder instead, fighters can get critical hits more often, and thiefs can slow and enfeeble with backstabs. Bards actually get a complety separate spell list, with a mixture of mage and cleric spells. No more pointless race/class limitations, so Mazzy can be a real paladin. The multiclassing system in 3rd edition will prevent some of the cheesier class choices like assasin dualed to a mage, or Kensai mage which could walk through most of the game when they came into their power, while allowing nearly any combination desired. Then there is the lure of sub-races, many will enjoy playing BG2 as a Drow, Aasimaar, Teifling, or perhaps Duerger. Hope that helps.