Tim Sweeney is as well-known for his opposition of Microsoft’s Universal Windows Platform (UWP) as he is for being the co-founder of Epic Games and co-creator of the Unreal Engine. After he claimed the UWP initiative was turning the PC into a walled garden earlier this year, Sweeney now warns that future Windows 10 updates will result in Steam becoming a buggy mess, making the Windows Store a preferable alternative.

Speaking in an interview with Edge magazine, Sweeney claims that Microsoft could slowly break and phase out long-used Win32 applications as it convinces developers to use its UWP model.

There are two programming interfaces for Windows and every app has to choose one of them. Every Steam app – every PC game for the past few decades – has used Win32. It’s been both responsible for the vibrant software market we have now, but also for malware. Any program can be a virus. Universal Windows Platform is seen as an antidote to that. It’s sandboxed – much more locked down.

The risk here is that, if Microsoft convinces everybody to use UWP, then they phase out Win32 apps. If they can succeed in doing that then it’s a small leap to forcing all apps and games to be distributed through the Windows Store. Once we reach that point, the PC has become a closed platform. It won’t be that one day they flip a switch that will break your Steam library – what they’re trying to do is a series of sneaky maneuvers. They make it more and more inconvenient to use the old apps, and, simultaneously, they try to become the only source for the new ones.

As for Steam, Sweeny says the numerous Windows 10 patches Microsoft plan to introduce over the coming years will make the digital storefront “progressively worse and more broken,” until the Windows Store becomes a better option for buying games digititally. He claims Microsoft already used this method with its competitors in other markets, though he didn’t go into specifics.

Steam is, of course, the digital store of choice for the vast majority of PC owners, and despite some recent improvements, UWP games are still arriving on the Windows Store with plenty of performance issues. So is it really that far-fetched to imagine Microsoft intentionally hamstringing Steam over the next five years? Possibly not. But even if it did, doing so could result in many people still refusing to switch over to the Windows Store, and it may even see more users turning to Linux.