Thomas began his career at Interplay working on Starfleet Academy, scripting missions as well as designing/scripting multiplayer modes. While finishing the game, he also assisted in fixing bugs in Fallout. After that, he was transferred over to the newly-created Black Isle division to work on Fallout 2 as a scripter, where he worked on areas like New Reno, Modoc, & The Den. After F2, Thomas went on to work on all the Icewind Dale games as a programmer before being convinced to try his hand as an associate producer.
After several key players left Black Isle to form Obsidian, Thomas took over production responsibilities on projects Jackson and Van Buren, both which never saw the light of day as Interplay pulled the plug on BIS.
After that, Thomas started work at Pandemic Studios as a designer on Mercenaries for the PS2 and Xbox. After that, Thomas was promoted to Lead Designer and worked on The Saboteur.
In 2011 he joinned Microsoft Game Studios as Design Director, working on Kinect related games.