It seems pretty easily moddable, just based on how many mods there already are for it.
On nwn2, you can literally recompile the code of most spells. If you know the basics of structured programming, you can change a lot how things are.
The devs picked black tentacles/chilling tentacles and nerfed the Caster Level + 8 BAB to hit to a fix +5 turning it worthless against highly armored enemies? Any freshman on programming 101 can fix this problem. BG2 in other hands is extremely hard to mod. WeiDU is pretty hard and confusing to be used. I know cuz I tried to learn how to mod BG2 and failed miserably. NWN2 also has a lot of player made campaigns. Is not like "dungeon master" mode in other games, there are conversions from P&P modules and far more content. Despite BG2 being my favorite game, the amount of player created content makes me have played far more NWN1/2.
