Before working at Bethesda, he was a designer on the Thief series, and worked at Looking Glass and Ion Storm Austin. At Bethesda, his first task was creating all the miscellaneous quests for Bloodmoon, the second official Morrowind expansion. Then he did a lot of design work on Oblivion, including the Arena and Dark Brotherhood.
When put to work on Fallout 3, he brought more of his seemingly dark thoughts to the game. One of his ideas was suggesting the Pint-Sized Slasher for the evil end to the Tranquility Lane quest, which, when finished, allowed you to exit the simulation.