TL;DR: I am preparing a PnP adaptation of Baldur's Gate. Have you done something similar? What was your experience? Did you do any major plot changes? Any advice?
Baldur's Gate series is one of my favourite video games. So when I found out that none from my PnP group had played the original games I thought I would run a campaign based on it and they were very keen on the idea.
BG, while being an epic cRPG, it requires some changes to make it work. It is combat heavy, it has some plotholes, underdeveloped quests, it has companion NPCs and fetch quests that are not necessary in a PnP game, and it can be railroady (obviously limited by the options programmed in the code).
My intention is to use the main quest line (iron crisis/bhaalspawn saga) and some interesting events/subplots, and build up from there. Essentially use the game as a base frame rather than adapt everything 1:1.
The premise is that all PC's are bhaalspawn. The Harpers wanted to keep an eye out for them and manipulated their lives to bring them to Candlekeep, to be vetted and monitored by Gorion. (who generally has a darker role and fakes his death). So not all of them grew up in Candlekeep but they have ties with him. The game begins after the ambush site from which point on, the PC's are free to explore the Sword Coast (hexcrawl with areas and events not just from the BG game) and engage as much or as little as they want with the main plot.
There are several walkthroughs online that detail the different areas, quests and NPCs of the game, and several published books that deal with the Sword Coast and the city of Baldur's Gate (Murder in BG, Descent into Arvenus, Heroes of Baldur's Gate, Volo's Guide to the Sword Coast) so in terms of source books and lore I think I'm covered.
I'm looking for is your ideas and advice on the following areas:
1. Have you done something similar, with BG or any other video games? How did it go? Challenges? Any general advice?
2. What were the major story changes you did? E.g. In my case one of them is that I'm going for a group of bwaalspawn instead of a single Gorion's ward.
3. What do you think are some glaring plotholes of the game? How would you fix them?
4. What were some quests/plots that you found underdeveloped/shallow. How would you develop them. The unfinished business mod deals with some. Anything else you can think of?
5. Certain events are railroady. e.g Duke Eltan offers you a quest you can't turn it down or you die. Which other examples can you think of and how would you allow more player agency.
6. The world should not revolve around the PCs, but in game it does. People should go about their business and events should unfold in the background even if the PCs are not there to witness them. How would certain such events unfold if the PC's don't intervene in time. E.g. If the party fails to attend Sarevok's ceremony and he is crowned Grand Duke, or if Sarevok flees but the party decides not to chase him? Any other cases you can think of?
7. What are some quests that don't make sense. How would you change them? E.g. Landrin and her spiders. In game you find her in FAI, yet her infested home is in Beregost. So she travelled 24 hours of dangerous bandit infested roads to seek out mercenaries... I turned her into a wizard's apprentice that experiments with spiders went wrong and moved her to an inn in Beregost.
Please let me know what you think. If people are interested (and if this idea takes off) I could post the tweaks to the story here.