Here’s a great research on Linux sales on Steam from Gamasutra:
“The question on everybody’s mind is : how many Linux users are there anyway (on Steam)?
Nearly three times as many Linux sales as Mac sales, Linux (for desktops) is a much smaller market than Mac. There’s several possible explanations for these results – pent-up demand from Linux users, Defender’s Quest being one of only a handful of Linux games available, and the Linux theme of the promotion itself.
There’s also the possibility that we’ve simply been under-estimating the Linux market all along (especially considering the results from the various Humble Indie Bundles).
Methodology matters just as much as raw data, so here’s how Steam calculates “linux” and “mac” users: “Mac/Linux sales are based on platform of purchase; or after 7 days, the platform with the most minutes played.”
That’s pretty straightforward, except for an ambiguous edge case – what happens if someone buys the game on Windows, plays for a minute, and then logs 60 hours on their Linux box 10 days later? Are they counted as a Windows user or a Linux user? (I’ve written to Valve for clarification on this). I’m not sure there’s enough cases of this sort of thing to grossly affect the data.
In any case, data from a one-week, Linux-themed sales period isn’t exactly typical, so I compared these results to our lifetime direct (non-steam) sales stats. These numbers only account for sales made directly through www.defendersquest.com. Whenever someone purchased the game from our site, they got links to Windows, Mac, and Linux builds of the game. Our storefront software, FastSpring, tracks how many times users click on each link.
Just as on Steam, Windows clearly dominates, and at least for our direct sales, Mac has a slight lead over Linux.
Our Linux builds came in three flavors – DEB, TAR.GZ, and RPM, to accommodate the various different Linux distributions. Of these, the DEB package accounted for 52% of downloads, the TAR.GZ had 36%, and the RPM package came in last at 11%.
This data set accounts for overall download attempts, not individual users. Our storefront provider, FastSpring, lets user download each file up to 6 times before a fixed expiration date, after which we have to manually reset the link at the customer’s request. (Needless to say, this “feature” makes me want to replace FastSpring at the first opportunity).”
For conclusions and more head over to Gamasutra.