Valve's Big Picture Mode for Steam - a custom-built TV display for the company's leading PC platform - is said to have accumulated more than 500,000 users.
John Clark, who works at Sega as vice president of digital distribution, made the claim at the London Games Conference in front of a packed audience of industry delegates.
During a presentation about the lessons Sega has taken onboard with digital distribution, Clark also revealed that Steam has accrued some 50 million registered users.
Valve has not verified all the data in an official capacity, though Clark and Sega work closely with the PC games giant.
Meanwhile, Clark revealed that the Steam edition of Football Manager 2013 had outsold its predecessor by 117 per cent on launch day. He said that a closed beta for the game, offered to users for free before launch, had generated significant publicity for the game.
Sega's Football Manager helped a 21 year old student from Sweden successfully land a job as the manager of the Azerbaijani Premier League club FK Baku's 'A' side.