Warren Spector and others discuss Underworld Ascendant’s Improvisation Engine: “Our designers lay out an encounter; setting up the monsters, traps, the physical layout, and the like. Then the world simulation is turned on. A set of fairly complex interactions and dynamics take place of their own accord. The player comes into this dynamic mix, and can permeate this situation in whole range of ways, some of which the designers may have never imagined.”