Tim Sweeney is still mad, but you'd never know unless you asked him about the potential threat of Windows becoming a closed platform. On the loud Game Developer's Conference expo floor on Wednesday, we spoke about the Unreal Engine, what's pushing the technology of games forward, and, of course, Universal Windows Apps. Sweeney made big waves last year with an editorial decrying Microsoft's move with UWP, and continued to criticize it throughout the year. Since then, Microsoft has released several UWP games on Windows, but little has changed with the Windows Store since Sweeney's original criticism.

So I asked him what he thought. Had Microsoft assuaged any of his concerns with the platform? If not, what would it take?

"Well, I should be very clear," Sweeney said. "The thing that I feel is incredibly important for the future of the industry is that the PC platform remains open, so that any user without any friction can install applications from any developer, and ensure that no company, Microsoft or anybody else, can insert themselves by force as the universal middleman, and force developers to sell through them instead of selling directly to customers. I’ve been selling games directly to customers since 1991 when I was mailing out floppy disks, and when you take that power away suddenly you have onerous certification processes, you have a distribution monopoly that tends to move towards an advertising-centric sales model.

"Look at the experience of searching for a game on iOS now: the advertisements for the games you’re not searching for appear before the actual stuff you’re looking for, and it’s a real shame that we’ve let closed platforms get to that point. And we have a very small set of free platforms open now—there’s Windows, there’s Linux—and we’ve got to do everything we can to defend them."

Sweeney balanced his criticism by saying that the UWP technology itself is neutral, calling it "a safer set of APIs for Windows" and saying that "if Microsoft would absolutely commit itself to making UWP available, in the long run, in as open a way as Win32 is today I think it would be a positive thing for the industry. We’d support it in that case."

Microsoft has improved UWP since its initial rocky launch with Tomb Raider and Quantum Break. It added support for G-Sync and FreeSync and unlocked framerates. Gears of War 4 ran fantastically on PC and shipped with a huge range of options.

But some of the larger concerns remain. Microsoft cited protection from malware and other malicious code being injected into games as a benefit of UWP's safer sandbox. That safety comes at the cost of making games harder or impossible to mod without built-in developer support, however. And anecdotally, I've used mods in many, many games, but I don't think I've ever gotten a virus from one.

Sweeney called malware "an excuse."

Malware is an excuse. Tim Sweeney

"All of the things that Microsoft can do to make Windows more secure, they can do without forcing everybody to sell their stuff through their store," he said. "And so, all of these claims that they’re forcing people into the Windows Store and adding friction to non-Windows Store software purchasing, it’s just a lie when they say that they’re doing that to secure users. Those are two completely separate issues that they’re only conflating because it’s the only possible excuse they can use for their efforts. But yeah, UWP is a very, very long way from being able to support the kind of openness and flexibility of PC games today.

Epic Games sells and releases games through its own launcher.

"Modding is one issue, being able to load code by modders into your process and have that become part of the game experience. It’s a fairly complex ecosystem. And also the ability to run tools, the Unreal Editor, Photoshop, Microsoft Visual Studio, or even Microsoft Word—none of those apps run on UWP. Microsoft Word does not run on UWP. It’s not even in the fucking Windows Store, because the Store and the UWP foundations are not capable of supporting that level of app.

"So, they’re trying to force this thing on the industry and it’s woefully inadequate for the tasks they’re trying to serve it for. What it has worked well for are these small apps like the Twitter client, or the Dropbox visual client, which are mobile levels of app functionality, as opposed to desktop levels of app functionality."

Microsoft hasn't yet moved all of its games to the Universal Windows Platform, and has allowed some partners to release games on PC through Steam and other stores. Quantum Break, for example, got a Win32 release on Steam not long after it first released the Windows Store. Ori and the Blind Forest and Rise of the Tomb Raider are available on both. But it's true that, so far, we haven't seen Universal Windows Apps distributed in any significant way outside the Windows Store.

On Thursday Microsoft gave me a demo of some changes to its Xbox software for Windows 10, and I asked about any recent discussions around UWP at Microsoft, and whether moddability and distribution outside the Windows Store were under consideration. Senior product manager Peter Orullian spent a few minutes chatting about UWP before we continued the demo.

Microsoft's Gears of War 4 had a great selection of PC display options.

"Totally, I've heard feedback from gamers and the Tim Sweeneys of the world around UWP," he said. Orullian said that UWP was designed with safety in mind, and that as a result some UWP features weren't initially available. G-Sync and SLI were two Microsoft addressed last summer. "We aren't making any announcements, but we are actively looking at other things like overlays, FRAPS, mods, all of those things are under consideration for how we continue to evolve UWP. We've heard the feedback, and we're far from done evolving UWP."

What about distribution?

"There's no policy or technical reasons why UWP can't be sold anywhere, on our side," Orullian said. "I think that other ecommerce sites may have their own feelings on whether they want to carry UWP. That's up to them."

There's no policy or technical reasons why UWP can't be sold anywhere, on our side. Microsoft's Jason Orullian

Orullian pointed out that UWP is a nascent platform, while Win32 is a mature one that has its own problems. "The things that gamers want, developers want, we're going to inherit those from Win32. But it also comes with a bunch of benefits. One of the things with Game Mode is that while it's going to apply to both Win32 and UWP titles, on UWP because of the architecture, we know where the game starts and stops. So our ability to look at the file and optimize with Game Mode to provide performance benefits is much greater than Win32 where it's kind of chaos inside the package."

So there are advantages that ultimately we gain with UWP, and on the Win32 side, the things you're able to do there are things we've already deployed or are actively investigating for future releases. And that's not a defensive statement. If you or your readers want to provide more feedback on elements of the UWP platform that they are seeing or enjoying as developers or gamers, that are part of Win32 that are gaps for us, we want to hear about it. I say that genuinely because I work on PC gaming at Microsoft."

What about Linux?

In response to the Windows 8 store, Valve began a big push for Linux as a more open alternative for PC gaming. That strategy culminated in SteamOS and Steam Machines, which have—look, I'm sorry, I just have to say it—lost steam. They still exist, and game engines today make it much easier to port to Linux than they did five or 10 years ago. I asked Sweeney if he thought Linux could really be a viable alternative.

"I think it’s important to recognize that Linux is actually the number one consumer device operating system in the world right now [through Android]," he said. "And so it is quite possible that it could take over consumer computers also. If you look most of the major apps are very close to being able to ship Linux support on par with Windows, and we’re just lacking maybe a few formative industry events to push us over the hill, such as these maneuvers by Microsoft."

Sweeney mentioned that both Unreal Engine 4 and Unity support the open Vulkan renderer, an alternative to DirectX, which is key for Linux support.

But Linux still has an approachability problem. "With Android, Google is the proprietor of this fixed version of it that is highly polished for consumers, makes it available to all the carriers and they distribute it. There’s no equivalent to that on PC, so the process of obtaining Linux is actually really, really tricky. That’s going to be a barrier to consumer adoption until something changes there … You really need something like the Android user interface shell to make it readily accessible by ordinary human beings."