He first started working at Disney Interactive, where he was part of a group that developed the basic design of a game that eventually became Epic Mickey. Sean later moved to Telltale Games. At Telltale Vanaman was the co-project leader and head writer of The Walking Dead.
Vanaman was also one of the co-hosts of the Idle Thumbs podcast.
On September 19, 2013 he co-founded a new independent studio named Campo Santo with Nels Anderson, Jake Rodkin, and Olly Moss. In April 2018 Vanaman and his colleagues at Campo Santo joined the Valve Corporation where they continue their work on what would have been Campo Santos second game In the Valley of Gods.