For me, one of the better RPG element of the examples he gives (Fallout/Elder Scrolls) was schedule-driven characters. If their response had been driven by the time of day, that would have been even better. Second up were the presence of interactive NPCs with a story to tell but who weren't part of the main story line, and who you could actually give a darn about. Third was a change in local or world circumstances due to actions you have taken. Stuff that adds to the sense of immersion. Despite all that though, I connected much better with my character when I could build him (or her) from the ground up and control his advancement in detail. FO3 did that very well, at least with the intro.