I also don't think it feels like 90+% these days. My own steam profile says 144/323 games support Linux, plus I've got some number more Linux capable games from

I also don't think it feels like 90+% these days. My own steam profile says 144/323 games support Linux, plus I've got some number more Linux capable games from bundles that I never imported into Steam but either played on desktop or in some cases the mobile version. (Then there's the "classic" Linux games from the dark ages that I really liked a lot like Battle for Wesnoth, Tremulous, and BZFlag.) Of course of the steam ones, I've encountered several that either flat out didn't work on my system (probably the hardest part of shipping linux binaries is testing for many distros and setups, SteamOS/Ubuntu gets you most of the way there though) or they worked poorly. So most of my gaming is still in Windows 7 but I don't really use that OS for other stuff. Of those 144, I've played maybe half of them (my backlog is huge..) but mostly not on Linux. Either because they didn't support it when I played (Half-Life games as probably the oldest example) or I tried and it didn't work [well] or I just didn't even bother trying. Even for the engines that don't support one-click Linux (or Mac) builds, it's not an insurmountable effort to support Linux, and if the game was already targeting multiple consoles+PC they've probably abstracted most platform specific stuff already. So it's just an economic issue. A lot of the technological issues have been mitigated or gone away.