Tim Sweeney, the co-founder of Gears of War maker Epic Games, has launched a blistering attack on Microsoft over its Universal Windows Platform (UWP) initiative. In an op-ed he penned for The Guardian, Sweeney claimed that UWP is “the most aggressive move Microsoft has ever made.”

Microsoft launched UWP as a way for developers to create apps that run on multiple types of devices, such as Windows 10-powered PCs, mobiles, tablets, and even IoT products. All UWP applications must be sold through the Windows Store where Microsoft takes a 30 percent cut.

Sweeney says that as Microsoft has launched features exclusive to UWP, the company is "effectively telling developers you can use these Windows features only if you submit to the control of our locked-down UWP ecosystem.”

"They're curtailing users' freedom to install full-featured PC software, and subverting the rights of developers and publishers to maintain a direct relationship with their customers," Sweeney said.

Earlier this month, Xbox head Phil Spencer talked about the benefits that UWP will offer developers, especially when porting games and apps across Microsoft devices. “Our goal is to make UWP [Universal Windows Platform] the best platform for game developers and gamers to support, but we know we’ve got room to grow,” he said in an interview with PCGamer.

But Sweeney has hit out at the company, accusing Microsoft of "structuring its operating system to advantage its own store while unfairly disadvantaging competing app stores, as well as developers and publishers who distribute games directly to their customers.”

“The specific problem here is that Microsoft’s shiny new ‘Universal Windows Platform’ is locked down, and by default it’s impossible to download UWP apps from the websites of publishers and developers, to install them, update them, and conduct commerce in them outside of the Windows Store.”

Sweeney did acknowledge that if you dig far enough into Microsoft’s “settings-burying” UI, it was possible to install UWP apps by enabling side-loading (loading onto other stores), but as this is disabled by default, Sweeney claims Microsoft is unfairly disadvantaging the competition.

For its part, Microsoft’s vice president of Windows, Kevin Gallo, repsonded with the following statement.

The Universal Windows Platform is a fully open ecosystem, available to every developer, that can be supported by any store. We continue to make improvements for developers; for example, in the Windows 10 November Update, we enabled people to easily side-load apps by default, with no UX [user experience] required.

Microsoft seemingly turning the PC into a walled garden isn’t going down well, and may lead to more developers publicly backing Sweeney’s views. "Unless Microsoft changes course," he says, "all of the independent companies comprising the PC ecosystem have a decision to make: to oppose this, or cede control of their existing customer relationships and commerce to Microsoft’s exclusive control."

Sweeney’s words follow the recent outcry over revelations that Microsoft-published Quantum Break will only be available as a UWP application exclusive to Windows 10 and sold via the Windows Store. Currently, UWP app limitations include not being able to turn off V-sync, a lack SLI and Crossfire support, and no .exe file for use with Steam.

“Universal Windows Platform can, should, must and will, die," said Sweeney.