Why did Microsoft buy Minecraft for $2.5 billion?

The most obvious reason is that video game is a massive hit: Created by the Swedish game company Mojang, it earned a hefty profit of $125 million on sales of $317 million in 2013.

But now we are hearing from Microsoft that there was another motivation behind the big-ticket purchase.

Xbox Games Chief Phil Spencer said in an interview with EuroGamer following his appearance at GDC that Minecraft is playing a key role in unifying all of Microsoft’s platforms as part of Windows 10. Minecraft players can play the on multiple devices, including PCs, Xbox consoles, PlayStations and mobile device.

That’s an ideal use case for Windows going forward, which will enable gamers to stream games from their Xbox One to a PC or tablet for the first time.

“That’s why Minecraft made sense – it’s a viral thing across so many screens, and it’s a conduit for us to learn about what does it mean when people touch your service across all these different screens and what do they expect,” he said. “It’s something that’s come together over the last year.”

The reporter went on to ask if the unification that Windows 10 is bringing was always planned as part of the Xbox One’s offering.

“Honestly, it’s new,” Spencer said. “The original vision around Xbox was to deliver a great gaming console that would also be useful for TV and other forms of entertainment, which could lift it to a huge install base and success.”

While Minecraft is a good example, the strategy won’t necessarily work for all games, Spencer added.

“It’s not something we’re forcing, that a game has to support all the platforms, but more developers than not when we talk to them about the opportunity see it. Why wouldn’t they want someone playing their game whether they’re at home or at work, on their laptop on their television. I want that television experience to be unique and special, and you can do that with the Xbox One, but I also want them to be able to play it wherever they are,” he said.

[Update: An earlier version of the story suggested that the same game could be played cross-platform, but currently that feature does not exist. Additionally, a Microsoft spokesperson says that Microsoft has not announced that Windows 10 will enable players to play Minecraft cross-device on competitive platforms, including PlayStation.]