Blume co-founded Tactical Studies Rules (TSR) with Gary Gygax in the early 1970s.  It published the first edition of Dungeons and Dragons, designed by Gygax (who passed away in 2008, see “Gary Gygax, 1938-2008”) and Dave Arneson (who passed away in 2009, see “Dave Arneson, 1947-2009”) in 1974.

Blume, along with his brother Kevin, remained active in the company until 1985, when the brothers sold their shares to Lorraine Williams.  Blume was active in promoting D&D internationally, and with his brother helped expand the company into toys, miniatures, and other licensed ventures. 

Blume co-authored D&D supplement Eldritch Wizardry with Gygax, worked on The Rogues Gallery, co-authored the Warriors of Mars miniatures wargame adaptation and the Boot Hill RPG with Gygax, and wrote the Panzer Warfare miniatures wargame.  Blume also worked as a cartographer after leaving TSR, primarily for White Wolf.