Facebook (NASDAQ:FB) CEO Mark Zuckerberg's love of all things mobile is nothing new. Zuckerberg and team have spent much of the past couple years focused on making the social media site as friendly for mobile devices as it is for desktop computers. And with over 1 billion of Facebook's 1.32 billion monthly average users accessing the site via mobile devices, clearly Zuckerberg's efforts are working.

That focus on mobile goes beyond Facebook itself and business units such as Instagram or WhatsApp. Now that virtual reality, or VR, device maker Oculus is part of the Facebook family, you can bet making its cutting-edge Rift VR device compatible with the world's mobile devices is near the top of Zuckerberg's to-do list.

With a little help from Samsung (NASDAQOTH:SSNLF), Oculus developed the soon-to-be-released mobile VR headset called Gear. This is a great step in Oculus' mobile VR ambitions, but there may be a major hurdle to overcome before a mobile Rift device goes mainstream.

A few Gear specs
The vast majority of Samsung's smartphones use Google's (NASDAQ:GOOG) (NASDAQ:GOOGL) Android operating system. No surprise there, considering that 84.7% of the world's smartphones sport an Android OS. Oculus developers got a crash course in Android as they worked with Samsung's new Gear VR. The result is a headset with a slot for users to slip in Samsung's newest phablet, the Galaxy Note 4, push a "start" button, and leave reality for a while.

When the Gear is rolled out by year's end, assuming everything stays on schedule, it will only work with Samsung's Galaxy Note 4. Why just the new phablet? Therein lies a potential roadblock for Oculus as it moves to bring its own Rift VR solution to the mobile masses.

A VR developer's nightmare
As it stands, Oculus' Rift VR headset is perfectly compatible with a PC or laptop running Windows 7 or newer, or a Mac OS 10.8 or higher. Simple enough, and it covers most of the world's desktop computers. But Oculus engineers were forced to become immersed in Android's open source OS to make Samsung's Gear operational. Most, as it turns out, were new to Android, having spent the vast majority of their time readying the Rift headset for PC prime time.

Part of what makes Android OS so wildly popular -- being open source, developers are able to customize and tweak it for different mobile devices -- is also a huge headache. As Oculus Chief Technology Officer John Carmack said of working with Android for the first time, "I don't think anyone is going to say great things about being a native developer on Android." Carmack added that developing in Android is "no fun at all."

What's the problem with Android? Carmack said his biggest Android development headache is that since Google has to support such a "diverse hardware spectrum," it doesn't really endorse developing native code, meaning engineers are essentially forced to code Android Google's way.

But the hurdles Oculus developers were forced to overcome, and are still challenged with, due to Google's constraints on Android pale in comparison to an even bigger problem going forward. How does Oculus develop a mobile Rift headset that is compatible with the world's most popular OS, on innumerable devices, each with its own tweaked version of Android?

Based on its experience with developing Samsung's Gear, which required mastering just one version of Android, getting a mobile Rift to a wide market is going to be a major headache. As it stands, Oculus doesn't appear close to being able to solve the multiple Android OS problem, and let's face it, a mobile solution that is not compatible with Android is destined to fail.

Final Foolish thoughts
It may be a bit early to start fretting over a mass-produced mobile Rift VR headset that won't work with nearly 85% of the world's smartphones. After all, Oculus is still working on bringing its PC-based VR solution to the masses. But we know Zuckerberg loves mobile, and the market is simply too big to ignore. The Samsung Gear is a great step in the right direction for Facebook's Oculus, opening the door to a world of virtual possibilities. But developing a widespread Android-compatible solution isn't just a nicety, it's an absolute must if Oculus plans on becoming anything more than a mobile niche player.

Tim Brugger has no position in any stocks mentioned. The Motley Fool recommends Apple, Facebook, Google (A shares), and Google (C shares). The Motley Fool owns shares of Apple, Facebook, Google (A shares), and Google (C shares). Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.