He was the senior game designer of sound and music at Valve[1] until he left in 2011 with Mike Dussault to concentrate on their project, Sunspark Labs LLC.
"[2] On Valve's official website circa 1998, his function was described as follows: "Kelly, formerly a product unit manager at Microsoft, has a programming background that includes consumer multimedia, database engines, and networking.
"[3] In addition to composing the soundtrack for Half-Life 2, Bailey was one of four Valve employees – the others being David Speyrer, Eric Kirchmer, and Greg Coomer – who served as facial models for Gordon Freeman's face in the game's promotional materials.
"[5] Around March 2011, Kelly Bailey left Valve with colleague Mike Dussault to work on their project Sunspark Labs LLC, launched in December 2010, developing iOS applications, their first being "Morfo", released in June 2011.
[6][7] The news caused some concern and displeasure from the Steam community due to the lack of any public farewell or notification regarding Bailey's departure.