Windows 10 seems to be having some trouble in achieving the milestones Microsoft set out for it back in 2015.

Company exec Yusuf Mehdi has told ZDNet that while Windows 10 is installed on "over 350 monthly million active devices," Microsoft does not expect that number to hit 1 billion by 2018, due (according to Microsoft) in large part to huge cuts company has made in its Windows Phone business. 

That undermines Microsoft exec Terry Myerson's ambitious claim, made at the company's 2015 Build developer conference, that Windows 10 would achieve an install base of over a billion devices in two or three years. 

This is notable for game devs because Microsoft has long pitched Windows 10 as a venue where developers can easily sell their work across PCs, consoles, smartphones and tablets.

"The reason why anybody would want to write universal apps is not because of our three percent share in phones," Microsoft chief Satya Nadella said in an interview last summer. "It's because a billion consumers are going to have a Start Menu, which is going to have your app. You start the journey there and take them to multiple places. Their app can go to the phone. They can go to HoloLens. They can go to Xbox."

The fact that the overall size of that Windows 10 ecosystem is not as large as Microsoft predicted it would be means there is that much less incentive for devs to bring their games into said ecosystem.