Later, he became the lead designer of a project codenamed Van Buren, which was canceled in 2003 and revealed to have been Black Isle's attempt at developing Fallout 3. During this time, he also compiled the Fallout Bible.After leaving Black Isle Studios, Avellone, together with Feargus Urquhart, founded Obsidian Entertainment. At Obsidian, Avellone has worked on such titles as Star Wars: Knights of the Old Republic II, Neverwinter Nights 2 and its expansion, Mask of the Betrayer, and was lead designer on the upcoming title Alpha Protocol. He is currently a senior designer on Fallout: New Vegas.
Chris Avellone got involved with the Fallout series when production was started on Fallout 2: A Post Nuclear Role Playing Game. While many feel that his "feel" for the Fallout canon was lacking, the design of New Reno has been praised by just as many.