The curtain seemed to fall on Steam Spy earlier this month thanks to changes in Steam's privacy settings, driven by the EU General Data Protection Regulation [GDPR], that set game ownership information to private by default. Without that information, Steam Spy can't work, and since none of us could be reasonably expected to go to the trouble of making our data public, that appeared to be the end of it.

That's not actually the case at all, however. In a new blog post, Steam Spy creator Sergey Galyonkin said that the changes to the Steam Web API that messed with his software were not actually caused by GDPR compliance: Real names, achievements, groups, screenshots, and friends are still public by default, and the Steam EULA hasn't been updated to comply with the new privacy regulations. The same is true of more recent changes to the Store API: "Like the previous change, this one wasn’t caused by GDPR compliance either — it’s hard to imagine Valve protecting the store’s privacy," Galyonkin wrote.

Valve hasn't told Galyonkin anything about the changes, although it confirmed receipt of a proposal he submitted about enabling Steam Spy to operate without exposing personal data—"More than they've ever said to me before," he noted. But what he did receive is more than 200 messages from developers telling him how Steam Spy "improved their lives."

"There was an indie company from Berlin that managed to secure financing from the government for their niche title because they had the data to prove that this niche is big enough. The title got released and succeeded," he wrote.

"Then there was a successful mid-sized publisher that entered the business after it was able to see which games are selling and which don’t. And then there were your usual stories of developers being able to navigate the space because they knew how the market behaves now."

That led him to return to Steam Spy for another look, and powered by his long-ago experience as a Ph.D. candidate ("predicting economic outcomes based on accidental data that might be irrelevant to the predicted results using machine learning") he found that he was able to come up with a resurrected system that "kinda works."

Most of the old Steam Spy features will be brought back, although a lot of it isn't working yet. The bigger issue is accuracy: Galyonkin said he has data for about 70 games from different developers, and the new Steam Spy is within a ten percent margin of error for 90 percent of them. It estimated Frostpunk sales of 252,000 units, for instance, and 11 Bit Studios announced today that it had achieved 250,000 unit sales, which is about as close to the mark as you can get without someone from Valve handing you an up-to-the-minute report.

"But I also saw some crazy outliers, where the difference between the estimates and the real data could be fivefold," he wrote.

Because of that, Galyonkin is keeping Steam Spy "semi-closed to the general audience" while he continues to work on the new algorithm and restore the core functionality. He also warned that Valve could make other changes in the future that will bring about the end of Steam Spy, possibly including the GDPR compliance that he assumed had caused all of this trouble in the first place.

"But until that happens," he wrote, "Steam Spy will continue to operate."