Maybe they have learned other developers' lesson that a it takes much more than a push of a button to get a Unity game on Linux.
QA takes time. Middleware may or may not be available. Launchers may not be there (especially in the case of Hearthstone). A lost of indie/kickstarted projects are still considered "Linux Scams" because they assumed that it'd be that easy.
it may not be easy, but with the progress made by other game engines in last few months, running your game on linux is now a reality and as easy as making it for PC (with little effort).
It sure is, I'm a Linux-exclusive gamer ever since Steam on Linux came out, but I try to look realistically at reasoning of developers who never did this before.
But then "Windows PC" would be the correct term. "Windows OS" would imply that it also runs on e.g. Windows Phone, which is usually treated separately.
Playonlinux makes it easy to launch Hearthstone and play it on any Linux distro. I have a hard time to believe that Blizzard does not have enough resources to do QA.
This is the biggest concern. The linux community is crazy hostile. Heaven forbid your game doesn't work on some wonky setup that would be 100% unreasonable to support. We also see this in Android where reviews for games are sometimes, "Zero stars, doesn't work on $49 $obscure_chinatablet."
Even if a company picked a reference Linux distro, like the current Ubuntu, it would be still displease a lot people, especially if the game only worked correctly on closed video drivers. There's really no winning in such a fragmented environment, unless you're willing to invest a serious amount of your budget here. Its not just "push a button."
What people seem to have a hard time understanding is that Linux is not an operating system, it's a family of operating systems. Someone running Gentoo with OpenRC and Xfce, someone running Debian with sysvinit and GNOME and someone running Arch with systemd and KDE are all "running Linux." This is more difficult than Windows or OS X, where you can rely on the low-level system plumbing staying the same from machine to machine (versions of OS X are all closer to each other than Linuxes are to each other and there's a lot fewer of them).
Valve are doing a lot to help here by distributing Steam with a known set of libraries that will be used by any games launched via Steam. There's still going to be some variation, but developers can at least know which version of key libraries they can rely on
I think their new refund policy will also help a lot. Being able to try a game to see if it works, and get your money back hassle-free if it doesn't, ought to take a lot of the anxiety out of the fragmented-target-OS issue.
Sure, the refund happens but now the devs have to contend with all the pissy reviews on their game's store page because the game didn't work with their very specific use cases. Its easier to just not bother unless you want to devote significant support and development resources to making the game run on any linux frakenputer.
I keep hearing we're crazy hostile and I don't see it. I have a crazy wonky linux setup and when games don't work, I don't flame the devs on messageboards. I even have a crazy wonky setup on windows - having a display with 240ppi, and I've seen plenty of games render badly, mess up my windows, etc. If it runs on Windows 8.1/latest Ubuntu on a beige Dell box, it's good enough for me, I'll always be able to work-around any problems.
You're talking about something completely different though; I'm talking about numerous releases/kickstarters which promised Linux support before they were funded, but then when they realized that it's harder than they thought they started saying "yeah, we didn't really mean «on release», it will maybe come later, or actually we outsourced it to volunteers", like with Divinity: OS or Skullgirls.
QA takes time. Middleware may or may not be available. Launchers may not be there (especially in the case of Hearthstone). A lost of indie/kickstarted projects are still considered "Linux Scams" because they assumed that it'd be that easy.