Underworld Ascendant - The Vision of an Immersive Sim

What exactly is an “immersive sim” and how's it different from a standard open world RPG? Check out the new developer diary for Underworld Ascendant with Paul Neurath, Warren Spector, and Joe Fielder to find out, and in the process learn a bit about Otherside Entertainment's unique legacy and Underworld Ascendant's plentiful connections to the Ultima Underworld games: