Stardock had estimated in its 2009 consumer report that Valve's Steam held 70% of the market by dollars generated while Impulse sat in second place with a 10% share, and all others--including the IGN-owned Direct2Drive--shared the remaining 20%.
"Stardock's recent assessment of its service is misinformation at best," Direct2Drive VP of digital content Sutton Trout told Gamasutra, citing a report by market research group NPD which painted a very different picture of the top during January-March 2009.
GamersGate has weighed in too, with CEO Theodore Bergquist telling Kotaku "We have daily direct contact with all major publishers out there, we can benchmark most of our numbers with both Steam and Direct2Drive, and we know for sure that Impulse is never up for discussion as being one of the biggest."
Stardock CEO and author of the consumer report Brad Wardell points out in a blog post that the NPD report highlighted by D2D does not paint a complete picture either, since it does not include figures from "Impulse, Gamers Gate, Metaboli or other competitors."
Bergquist offers non-specific figures of his own for GamersGate's standing in the digital sales realm, saying "in many, many cases we know that GamersGate sell as many units as Steam for the mid-size segment of titles."
While Bergquist notes "unfortunately I can't give you any specific numbers on titles", he expands "for AAA's we sell anything between half to a quarter. With a few exceptions they sell more than that. This is information we get from publishers direct from the source--their digital distribution teams."
The NPD Group report highlighted by Direct2Drive saw Steam topping the market with 50% dollar share, followed not by Impulse but World of Warcraft developer Blizzard's own store with 27%, according to Gamasutra's summary. Direct2Drive came in third by dollar share during the period.
While it seems unlikely that Blizzard's share would have dropped so dramatically as to fall beneath Impulse's estimated 10% share between the beginning of the year and the release of Stardock's report, Stardock's explanation that its figures are "based on discussions with publishers along with the numbers we are aware of" is as much of a disclaimer as it is a method.
Tracking digital sales is a difficult matter and, as Trout notes, "it's obvious there's a lot of guessing going on out there, and until the digital distribution market has a standardized reporting system in place, we'll continue to see these kinds of erroneous claims."
Direct2Drive is one of many corners of the PC gaming industry seeking better tracking, collation and reporting of digital sales, and Trout notes that D2D "is actively engaged with reputable data-collection services to determine how to most effectively implement standardized reporting in the digital distribution business."
Wardell meanwhile closes with the sage statement that "vendors publicly complaining about the right to claim they're #2 in getting the scraps Steam leaves behind look silly."
"The best thing these services can do is focus on making themselves better. Because they will need to be better if they want to effectively compete with Steam," he explains.
A large focus of Stardock's consumer report was its ongoing attempts to better compete with the Steam client by improving its own Impulse client and to lure publishers away from Valve's Steamworks suite--scorned by all three distributors--with its own Impulse Reactor.