Steam Spy is a new data tool developed by Sergey Galyonkin, which takes Steam’s publicly available web data and extrapolates information about Steam games and Steam’s user base. The information ranges from statistics for countries (how many users in a country use Steam, how many games the average user in a country owns, or how many hours they play, and so on) to data about games (sales over time, total number of owners, price fluctuations and how those affected sales, etc.).

In order to arrive at these statistics for Valve’s online marketplace, every minute, Steam Spy gathers data from a “limited number” of Steam users (about 150,000 valid profiles a day), and updates its visualizations every night. “The data is based on several days’ samples,” explains Galyonkin. “From three days for individual apps to seven days for location-based info. It means that Steam Spy is completely unreliable for recently released games.”

Galyonkin notes that “Steam Spy is often wrong. Not by much, but still wrong.” However, he also says he has been in contact with several developers who sell their games on the digital distribution platform, and claims they say Steam Spy isn’t far off in its estimations.

Assuming the data is correct(ish), we can now answer some questions we’ve had. For example, how well did Valkyria Chronicles really sell? Sega was happy, but wouldn’t tell us the number. That information’s above.

What about Cities: Skylines? How well has it done since its first-day sales, in comparison to the SimCity reboot? A month since its launch, it hasn’t performed as well as SimCity had by the end of the first two weeks. What does that tell us?

Specific games aren’t the only thing Steam Spy is good for. What if you wanted to know the proportion of Steam users according to region? And what can we infer from how many games users in a region own in comparison to others? What if we compare the two charts?

There’s also a Top 100 games list, which tracks data from the past two weeks for the most popular games of the period.

The project is a work in progress, still in alpha, so there are errors and bugs, and some of the data could be more usefully presented, but it’s still worth a look for those curious about PC games, the gaming industry, or the medium’s cultural reach.

If you’re interested, you can go play with the stats here.

(Thanks, Polygon.)