Quoting: Quote from Half-ShotThat looks like advance wars to me, shall be looking at this with interest :)

Why do many of the Steam Hardware Survey numbers seem to undergo a significant change in April 2012?

There was a bug introduced into Steam's survey code several months ago that caused a bias toward older systems. Specifically, only systems that had run the survey prior to the introduction of the bug would be asked to run the survey again. This caused brand new systems to never run the survey. In March 2012, we caught the bug, causing the survey to be run on a large number of new computers, thus giving us a more accurate survey and causing some of the numbers to vary more than they normally would month-to-month. Some of the most interesting changes revealed by this correction were the [increased OS share of Windows 7 (as Vista fell below XP)](http://store.steampowered.com/hwsurvey/#cat0),
the [rise of Intel as a graphics provider](http://store.steampowered.com/hwsurvey/#pcvidcard) and the overall diversification of Steam worldwide (as seen in the [increase of non-English language usage, particularly Russian](http://store.steampowered.com/hwsurvey/#cat9)).