Steam player data leak reveals detailed PC game sales data
When Steam announced that they'd be changing the way their user data was shared to comply with the recent European GDPR laws, Steam Spy, a site dedicated to estimating the amount of owners of Steam game, was rendered almost useless by the change. In the hopes of creating something similar to gauge amount of copies sold on the platform, programmer Tyler Glaiel ended up finding a new way to do what Steam Spy did, and in an even more accurate manner. His method required using Valve's Steam API to check achievement data for games and calculating the data to find the percentage of how many people obtained an achievement, and then use that to further find how many people had purchased a certain game. With the numbers provided by the API workaround, Glaiel was able to find the exact sales numbers of a large number of Steam games, so long as they had achievement data.
His method is detailed below.
This was brought up with a dev group I’m in, and it was quickly pointed out that if you get achievement data through steam’s API, you get 16 digits of precision instead! I set out to try and replicate barter.vg’s algorithm based on the description of it on their site, “Calculated by finding the lowest number of player that produces whole numbers of players for each achievement (percent achieved * all players)”.
So I got it working, with a simple brute force. Checked every possible whole number of sales up to a cap, and multiplied it by the achievement percentages. None of them exactly hit a whole number, so I had to set a threshold for what counts as a “whole number”. It worked for most games with less than a million sales.
When Valve had stated that they were working internally to find a better way of offering player data to users, this was not at all what they intended, and the data "leak" in the API was patched within four days of it being discovered. Prior to that, however, tech site ArsTechnica compiled all the offered sales data into a .CSV file and are hosting it on their site.
The file includes sales amount and data for games up until July 1st, and is the most accurate and detailed information dump to exist in regards to Steam. This also lets us see the highest selling or downloaded games of all time for the platform, of which Team Fortress 2 tops. Other games like Skyrim, Rocket League, Portal, PUBG, and more are also incredibly popular and have sold over 10 million on Steam alone.
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