At last week's Game Developers Conference in San Francisco, record numbers of industry players converged to showcase their latest titles. In full force were smaller, independent developers, showing off their indie games on a variety of hardware: Mac and Windows laptops, and iOS and Android devices.

Windows-based devices, however, were conspicuously absent—outside of the Microsoft booth, of course.

“I don’t like how Microsoft is restricting PC development with the Windows app store,” said Cavanagh.

This is troubling. GDC is the place where game developers and publishers convene to talk shop, and neither Windows 8/RT nor Windows Phone was a significant part of anyone's conversation. And while the Gaming category was one of the most promising sections of the Windows Store when we took stock earlier this year, we've also seen a sharp, sudden decline in new Windows app releases. This alone should have spurred Microsoft to ramp up its courtship of game developers, big and small.

I sat down with Microsoft representatives at the conference, and I'm confident that the people working on Windows understand how games are a critical component of any healthy app ecosystem. Nonetheless, Microsoft still has hard work ahead. Some indie game developers don't like Microsoft's business philosophy, while others haven't had access to the development tools they need.

Who can resist an 80/20 split?

Financially, it’s difficult to understand why developers are shunning Windows devices, as Microsoft offers a more generous revenue sharing agreement than either Apple or Google. Windows app developers get the better side of an 80/20 split after their apps break $25,000 in sales. That's a far more generous arrangement than the 70/30 split that iOS and Android developers receive.

Microsoft touts Visual Studio as a versatile tool that's supported by a legion of Microsoft staff, a claim backed up by the Windows 8 developers we've spoken to in the past.

Microsoft also says that the Windows Store is more welcoming than competing app ecosystems because Visual Studio—the development environment for building Windows apps—supports a broad variety of coding languages. And many developers seem to agree: When we talked to the first wave of Windows app developers last year, coders praised Microsoft’s tools and developer outreach efforts.

But that sentiment wasn’t shared by many indie game makers on the GDC show floor. To find out why, I canvassed the show asking developers what kept them from putting their products up for sale in the Windows Store.

Compatibility problems are easy to solve

Behold Studios makes Knights of Pen and Paper, a game for iOS (and soon Steam) that’s built in the Unity development environment. The folks at Behold are open to bringing their game to the Windows Store, but they can't because Windows Visual Studio can’t import Unity code—yet. This is a niggling problem for Behold, but it’s a huge problem for Microsoft because Unity is one of the most popular tools for small and midsize game developers.

Indeed, if the Windows team wants to beef up the number of great independent games in the Windows Store, it needs to start playing ball with Unity.

Knights of Pen & Paper is coming soon to your PC desktop via Steam, and now that Unity is poised to support Windows apps it could also be in the Windows Store before the year is through.

Microsoft is actually on top of this. During GDC, news broke that Unity is starting up a beta program for Windows 8 developers. So while the commercial version of Unity won’t be capable of compiling games for the Window Store for a while yet, Microsoft is working with the Unity folks to do right by game developers. And for its part, the Unity team is already working directly with developers to bring their titles to Windows. In fact, 14 Unity-authored games—including Buck Hunter, Gunpowder, and Drift Mania Championship 2—are already in the Windows Store.

Windows 8 still has an image problem

But some developers just aren’t interested in selling their wares on the Windows Store, no matter how nicely Microsoft asks. For them, it’s a question of ethics. To name just one example, indie developer Terry Cavanagh is leery of Microsoft’s attempts to build a closed software ecosystem on the PC.

Cavanagh was at GDC to showcase Super Hexagon, a mind-numbingly fast game originally built in Flash and released for free online, then later ported to PC, Mac, Linux, iOS, Android, and BlackBerry 10—basically every platform except Windows 8/RT and Windows Phone.

Super Hexagon code plays well with Microsoft’s Visual Studio, and the game could be brought to the Windows Store, but Cavanagh isn’t interested. “I don’t like how Microsoft is restricting PC development with the Windows app store,” said Cavanagh. And the promise of more users and a more lucrative revenue split couldn’t dissuade him. “If people want to play Super Hexagon on a Windows phone, they should buy a different phone," he said.

Blue Screen of Awesome Super Hexagon is available now for almost everything—except Windows 8/RT and Windows Phone. It's going to stay that way unless Microsoft mollifies app developers angry about Windows 8.

Cavanagh isn't alone. Many indie developers, including Minecraft creator Markus Persson, have publicly decried the Windows Store. They perceive Microsoft as an interloper, trespassing on the open platform of the PC to build a walled garden of Windows apps.

The critics' fears are justified in terms of Windows RT tablets, but, obviously, Windows 8 still includes a desktop that lets you run any traditional Windows application (or game) you please. Still, it's easy to understand their fears. If Windows Blue does herald the death of the Windows desktop, independent developers will have to go through the Windows Store to reach their customers, or else abandon the PC entirely. The upshot is that Microsoft must wipe away the stigma attached to the Windows Store if it hopes to bring a significant class of developers back into the fold.

And that means they'll need to double down on developer outreach.

Microsoft needs more-aggressive outreach

Scottish game developer Lucky Frame would be happy to bring its iOS game Bad Hotel to the Windows Store—if Microsoft would just drop it a line.

The game was nominated for a Best in Audio award this year as part of the Independent Games Festival, so developers from Lucky Frame were on the GDC floor all week, showcasing their game in a booth less than a thousand feet from Microsoft’s GDC business suite. Yet according to Lucky Frame’s Sean McIlroy, Microsoft never contacted his studio, or expressed interest in helping them bring Bad Hotel to Windows.

That Microsoft’s vaunted developer outreach effort skipped over an award-nominated indie game like Bad Hotel is worrisome. Microsoft desperately needs to bolster its understocked app store, and that means it needs to court every talented developer it can lay its hands on. Especially if that developer is showing off an award-nominated indie game in the very same building.