A week ago, indie developer Tyler Glaiel suggested a new method to estimate the number of copies a game had sold on Steam. He did so via a Medimum blog post, which gathered a fair amount of interest.
A week on, Steamed reports, onlookers suddenly noticed Glaiel’s method was no longer working. Valve had quietly taken action to render it useless. At no point had the company commented on Glaiel’s method, or explained what and why it was changing its systems to block it.
In brief, Glaiel suggested using the percentage of people who had unlocked a particular achievement to then estimate a game’s overall userbase. Steam counted achievement percentages to 16 decimal places.
Source: Eurogamer Valve quietly blocks new method to estimate Steam sales figures