Gaming on Linux is a tricky subject. The platform has always been subject to bad video drivers, ever-changing APIs and haphazard support for Windows games in Wine, which has a tendency to support an application just fine in one version and then suffer a regression in the next. But recently this has completely changed due to the release of Steam.
But its not so much that Steam is now available on Linux, but that mainstream gaming is slowly decaying on other platforms. For years now, the quality of high-budget games has been falling, which in turn is spelling the death of Windows and consoles as gaming platforms. Even Microsoft's latest XBox is more dedicated to social media than gaming. It has reached the point where you pay an insane amount of money for a game that is largely mediocre, linear and predictable, with most of its better content shoved into DLC.
This was entirely preventable, but like all companies, game developers tend to go too far in seeking profit, forgetting that their money doesn't come from happy magical money trees, but instead out of consumer's pockets. If you treat the consumers like idiots, or just a source of income, you do really well at first as your profit is maximized, and then it takes a nose dive off the deep end as your company suddenly finds themselves unable to cope with everyone hating you (I'm looking at you, EA!).
Its not like this happened overnight. Everyone saw it coming. Games just became more and more linear, each new sequel had less and less actual content, and the amount of hours of gameplay that you get after paying such a huge price has dropped to all-time lows. It has all become about how pretty the trailers are, how flashy the graphics are, and how famous your franchise is. Oldschool qualities like story telling, emotional drama and suspense, and dynamic environments are long gone. Games that were built on extremely limited engines, such as Doom, were far more dynamic than most modern first person shooters built with an engine a thousand times more advanced.
Many great indie games embody what gaming used to be. They recreate a world that most of us have long forgotten. The imagination and adventure that what has now become corporate greed has washed away. And between the rise of indie games, their ease of availability on Steam and similar distribution methods, the flourishing Android market, and the new Linux-based game console, Linux is set to take center stage over the next decade.
This may sound rediculous at first, but it is important to realize that the current gaming trends are bending violently towards indie games, and this is completely understandable. At first it was just happening on phones, but now even desktop users flock to indie games, such as the many available on Steam and in collections such as the Humble Indie Bundle. This has rendered Windows as a gaming platform almost obsolete. And consoles aren't too far behind, because they have the same problem.
Furthermore, Linux and Mac are just easier for developers. Lets face it, Windows development has always been horrible. The Windows API is perhaps one of the worst examples of design in computing history. And most of Microsoft's attempted replacements have not done much better. There's also the fact that DirectX is only used by one Operating System, and one console, while OpenGL and its variants are supported by quite literally everything else, including Windows main competitor - Mac.
And well, there's also the fact that Microsoft can't seem to stop shooting themselves in the foot with everything that they do.