I also quite disagree that the original Baldur's Gate games were a "very strict" adaptation of D&D in their day. Bioware took plenty of liberties, too.
We'll have to disagree on that -- they took the big liberty of making a turn based game into a real time with pause and, otherwise? Pretty much by the books. Which was quite the challenge because 2nd edition was anything but coherent being -- spun across multiple books and being contradictory in places. They even brought in things from the Zhakaria and Ravenloft settings. The house rules they used were largely the ones that most table top groups were already using -- no level caps on demi humans, letting good clerics use evil spells, etc.