Valve’s Pierre-Loup A. Griffais announced that they’re including their brand new fork of the WINE Windows pretendulator in a new beta product for Steam. They call it Proton. WINE is an open-source Windows API emulation layer that lets Linux users play Windows games without rebooting into Windows. I call this process “pretendulation” because it isn’t emulating the entire operating system, but it is still far from native.
That sounds good, more games for Linux, right?
Well, when I started writing about Linux gaming 18 years ago there was a commercial, closed-source, fork of WINE called WineX. WineX had a lot of fans, it was developed by people who had been working on Wine, which was a more generalized product for Windows software, to target game software. These developers of WineX (later called Cedega) did a good job at writing the software, but it had a number of issues.
One of those WineX issues was that Windows compatibility is a moving target. Any progress the WineX developers made to support new versions of Microsoft’s DirectX game software programming interface were usually still years behind where modern games were. If the latest Battlefield game came out and it only worked with DirectX 8 and WineX was still on 6 or 7, it was going to be a while until they could support that new game.
Even though new DirectX versions are less of a headlining feature in Windows these days, compatibility with a wide range of games is going to be a problem for Valve’s Proton as well.
Any emulation, or translation, layer, is also going to introduce some amount of performance overhead. You can’t emulate a PlayStation 3 or Dreamcast at full speed on a lot of expensive computers today, but you can buy the original console for $50 that plays those games perfectly. The same issue happens with emulating Windows APIs under Linux. Some games will only have a very small hit to performance, but others might be more of a problem and you won’t get the same framerate that you do under Windows.
So there are compatibility and performance issues, that’s it, right? Nope, there’s one more technical hurdle. When something breaks, you’re not going to know if it’s the game or the emulation layer. I imagine this will infuriate some developers.
Valve claims that games they’ve tested and whitelisted in this beta have an almost identical gameplay experience to Windows, and they acknowledge the performance overhead. Valve doesn’t acknowledge the negative effect this will have on real native ports of games. Back in those WineX days there were some developers and publishers who cancelled their plans for native Linux ports because Windows pretendulation was “good enough” for them, even when Wine or WineX didn’t provide a great experience for players.
“Good enough” Windows API emulation eventually turned into developers porting their games with Wine wrapped up into a library, giving Linux players some of the half-assed ports they have today.
One additional issue that wasn’t a problem with WineX, these improvements to Wine are only designed to work with games on Steam. You won’t be playing Battlefield 5 with Proton. Although Valve’s fork of Wine is open-source, unlike the old WineX fork which had its source closed behind an agreement that the executives at Transgaming later deleted and refused to acknowledge.
Proton is an interesting technology, but a bad thing for anyone who loves Linux gaming and wants native ports of games brought to Linux.