I played the first version 25 years ago and it was a real pain to finish. Eventually, after half a year of trying between long breaks, I finally managed to crack it. It is great to have a game that is not too fast and easy to play for a change!
I got stuck only once for a week or so, and had to search Internet for the glues. If happened with the mysterious flowery key. I looted it from shapeshifter Zomm in the cave behind the Open Hand Temple Cellar.

Without finding that place solving the Open Hand temple murder is not possible. Only after that I found Murder Tribunal and defeated Sarevok to get the Amulet of Bhaal which was necessary for accessing Bhaal Temple to kill Orin and get her netherstone. All three netherstones are needed for finishing the game.
In the end I ended up to hell accompanying Karlach as a vampire illithid, a Mind Flayer. I will surely play the game later again with a different protagonist doing the quests I skipped or failed on the first run.
Happy gaming,
Santeri