Immediately after his commencement, McComb took at a job at TSR, Inc., where he produced numerous role-playing game supplements and magazine articles relating to those games. He won an Origins Award for Best Game Adventure in 1993 for Dragon Mountain, and another for New Role-Playing Supplement for the Birthright Campaign Setting in 1995. He is primarily known for his work on the Planescape line, for which he and Monte Cook were the primary designers after the departure of David "Zeb" Cook from TSR.
In addition to his gaming work, McComb contributed interviews, album reviews, and concert reviews to the underground magazine Outburn. In 2004, he reunited with his Planescape cohorts in the Malhavoc Press book, Beyond Countless Doorways, which received an Honorable Mention for Best Writing at the 2005 ENnie Awards. He and his wife also designed and wrote the manual for the MMORPGRYL in 2005.