Valve sees 200 per cent growth in these alternative channels - not just Steam, but including the likes of cyber-cafes as well - versus less than 10 per cent in bricks-and-mortar shop sales. Steam has a 15 million-strong player-base with 1.25 million peak concurrent users, and 191 per cent annual growth; none too far off a console platform in itself. The PC casual games market, driven by the likes of PopCap, has gone from next to nothing to USD 1.5 billion dollar industry in under ten years, and has doubled in size in just three. Perhaps most surprisingly, Valve has found that digital distribution doesn't cannibalise retail sales - in fact, a free Day of Defeat weekend on Steam created more new retail sales than online ones.

And then there is the game that many claim has been the death of PC gaming, but that Valve sees as its greatest success story, and its future. "Until recently, the fact that World of Warcraft was generating 120 million dollars in gross revenue on a monthly basis was completely off the books," Newell says. "Essentially, [Blizzard is] creating a new Iron Man every month, in terms of the gross revenue they're generating as a studio. Any movie studio would be shouting about that from the rooftops. But it was essentially invisible."