These Open Source Devs Are Reverse-Engineering Xbox Game Pass for Linux

Xbox Game Pass has never really worked on Linux beyond laggy cloud streaming, but an open source project called Xodus is trying to change that.

Earlier this week, replying to a thread on Reddit, Paweł Lidwin (imLinguin), project lead of Xodus, confirmed that the hardest parts of running those games on Linux, Xbox authentication, and game downloads are already working.

The project is attempting to reverse engineer Xbox's entire authentication, licensing, and delivery pipeline well enough to run Xbox on PC and Game Pass titles on Linux.

What's Xodus?

Xodus describes itself as "the great gaming migration to Linux," while cautioning people that it is not endorsed by Microsoft and using it comes with risks. You see, modern Xbox PC games run on Microsoft's Game Development Kit, or GDK, and ship as encrypted⁣ MSIXVC packages.

Getting a game running on Linux means handling both.

The project's GitHub page currently houses a handful of repositories that include the main xodus client written in Rust, a forked ntfs library for reading MSIXVC, and xgameruntime, an open source implementation of xgameruntime.dll built for use in Wine.

A companion repo, xgameruntime-docs, documents how that same DLL works internally.

There's also forked copies of Wine and Proton, maintained by the Xodus team, featuring custom tweaks, and xal-rs, an Xbox authentication library forked from OpenXbox.

Keep in mind that there are no binaries available for you to play around with just yet; there's still a lot of work to be done.

So yeah, a First Look at Xodus is still months away. 😆

The devs are surprised

Thanks to that Reddit reply, the project has gotten a wave of press coverage, and it has caught the developers off guard. "Quite unexpected," wrote Paweł on the project's Discord server after Digital Foundry picked it up.

Though the original coverage seems to have been from VideoCardz.com, many of the outlets out there have got a detail wrong. Describing Xodus as a project from the Heroic Games Launcher team is not right, as Paweł is the only Xodus contributor who has also worked on Heroic, not the whole team.

Another contributor, BellezaEmporium, who has been busy tracking this surprise wave of coverage, points out that one of the articles has been quite salty in talking about Xodus, while Olivia (olivi-r) shared some important developmental updates.

She says that:

Progress has been fairly rapid the last few days on the xgameruntime side, XTaskQueue is nearly implemented with a few modes and quirks to sort out.

Currently fixing XUser as it seems the signature generation is a bit messed up 😬

Still need to actually load tickets from xodus into XUser as well, I've been hardcoding mine for the testing, not sure if we're going with the stdio proxy or ipc implemented directly in wine yet.

What now?

If Xodus pulls this off, it closes one of the last major gaps between Linux and Windows gaming. Game libraries on Steam, GOG, and Epic Games already run well through Proton and Heroic, but Xbox PC and Game Pass titles have been locked to Windows or laggy cloud streaming until now.

And, if you ask me, this is the right time for Xbox to make Xodus' job easier by lending a hand, similar to say how Valve has handled the development of Proton while supporting Wine and DXVK upstream. This way, the whole ecosystem benefits, not just Steam.

If Xbox decides to help the project, then they do have many avenues to pursue…