Arcanum. (with Drog's patch)
Somehow I've never played it. As a 90s cRPG veteran it is interesting to go fresh into a cRPG and be smacked with a lot of confusion about mechanics and stats that I don't have from games I'm used to playing. It took me a frustratingly long amount of time to figure out how to use the world map travel.
As seems to be a trend with Tim Cain games, the combat isn't very good but the game is carried by the social detail, world, and variety in how to approach quests. I'm going for a social build with a lean towards magic in order to get the most out of social interactions.