Some of my rules/gameplay changes ideas:
- redo pick pocket: don't turn everyone hostile (as thats nonsense - load a save), but call guards and give -1 rep or something... If you have a Paladin or other similar character then the reputation could fall even if PP succeeds (or Virtue introduced by Virtue mod). Paladin could even attack team-thief if he is close and see what had happened :D
- add minor magical items for currently underrepresented categories (like clubs, bard spellcasting armors in BG1 etc.)
- maybe alter AD&D a bit and give +1/2 attack per round (two times) to clericks and druids at a slower rate than for warrior-type classes, and even slower +1/2 for bards, thieves. (Description do say clericks are good fighters while 1 attack per round doesn't reflect that in AD&D)
- improve weak subclasses, balance or make more interesting few others (beastmaster, totemic druid, wizard slayer...)
- redo druid shape change to make it usable (scales with levels, better shape change forms). So at let say lv 1 druid can change into a plain wolf. At higer levels he goes to dire wolf, and up to snow wolf. At even higher levels the wolf stats do increase too. And also at bit higher levels he get bear line... and make animal weapons immune to dispel magic bug.
- both BG versions could have more less powerfull magical items - like +1 or +2 but with a extra bonus like poison dagger in BG1. It's doesn't do much damage, in BG2 it wouldn't hit some enemies (like a mummy even) but it has the interesting bonus. Everything more magical should be harder to get and not to early. In BG2 there is a nice set of such items but they are usually useless as characters have better already ;)
- Thieves and Bards should not have "Use Any Item" but instead reflecting gameplay better - use scrools and other gadgets, wands starting at lower levels if they have enough inteligence and wisdom. So for thieves let say 12 int for 1lv scrools, 14 for 2 lvl, 16 for 3-4, 18 lv for 5-6 lv max. (and it would be ubber cool if scrool containers would show spells in the spell menu for such characters - instead spellbook you see a list of spells=scrools you can use-cast). In BG2 you can notice that even low level thieves carry low level scrools often. Bards could be better at scribing scrools (they are bards after all) including clerical if wisdom is high.
- Idea for interesting Heart of Fury mode - instead of 1000 HP goblin just change mass enemies with much stronger enemies (designed to play with the same starting levels). Like a goblin may become a nasty wolf (snow one) or a skeleton warror. Orcs, hobgoblins,orogs... may became umber hulks, vampires, or even mind flyers side by side with elder orbs or gaunths. :D I did made a mod some time ago with that... turned out to be very evil:

- Optional Item randomisation: in one game you get Holy Avenger, in another holy armor and in yet another Holy Bow. (evil isn't it? :D) In such case your strategy may not be based on one specific item.