In October, Valve introduced a bug into Steam’s Discovery feature that made it recommend large, popular games instead of more relevant ones, according to developers affected by the problem. While the bug was apparently squashed quite quickly, the impact has remained, with a significant number of indie developers reporting a reduction in traffic and sales.

The issue has been going on for two months and there’s a forum thread (only developers who log in can read it) detailing it, but if you’re not a Steam developer, you can also read Shadowhand and Ancient Enemy developer Jake Birkett’s detailed account.

“I compared full price sales before and after the October bug (being careful to avoid week-long sales and Steam sales) and my total units sold have halved,” Birkett said in his blog post. “Revenue has dipped even more because our most expensive game has dropped to 36 percent of previous unit sales.”

Birkett informed a couple of Steam reps who said they’d investigate, but he’s still waiting to hear back from them. Other developers have also emailed their reps, he says, but haven’t heard any good news. Some indie developers he’s spoken with have not been affected, and some of them have even seen increased traffic, but the one thing that is consistent is that Valve is seemingly keeping developers in the dark.

When Valve announced was making changes to its revenue split that favoured big games and developers, reducing Steam’s take from 30 percent to 25 percent for earnings above $10 million, and 20 percent beyond $50 million, some indie developers expressed their frustration on Twitter, but Birkett is more concerned with the lingering problems from the Discovery bug.

Birkett’s tweet prompted several developers to share similar stories and accompanying graphs. Dean Hall noticed that Stationeers is getting 10 percent of the Steam homepage traffic that it used to receive, while Kingdoms and Castles designer Peter Angstadt said that daily sales dipped by 30-40 percent when the bug appeared, and they’ve not recovered.

Maia developer Simon Roth posted a screenshot of his traffic, revealing a drop to zero in early October and generally less traffic since then.

Roth assumes that the bug had a measurable impact on Maia’s launch. “Despite the big update, getting some coverage, having a huge number of wishlists and pushing many thousands of people to our Steam page, the ‘organic’ sales from the platform didn't really kick in,” he said in an email. “That probably wouldn't have been a huge number, but honestly, I'm the sort of dev where every single sale counts.”

Maia launched on November 23, nearly two months after the bug had been noticed and Valve reportedly fixed it. Unfortunately, all Roth can do is what others have done: email Valve and hope for a response.

The developer thread on Steam is now 55 pages long, the issue has been going on for two months and developers still don’t know if it’s a bug, the after-effects of a bug or a feature designed to shine a spotlight on a different kind of games. Valve won’t discuss the algorithm.

I've reached out to Valve and other developers and will update this story as it develops.