As for multi-version multi-instance there's no easy way to do this, at least not one I could find. I know two approaches to do this:
a) Multiple packages. Might require regenerating the .pri file (thanks to the other people for discovering that, including @abc-55 and @MisteFr). Breaks license and Xbox. No public way to work around either and there likely won't ever be (licensing can be bypassed with some effort, but afaik Xbox can not, someone would need to do some more research).
b) Single package, multiple versions. Done by moving the second version into a subfolder inside the appx, moving the second version data folder to a four letter one inside the main app (like dat2/), updating the AppxManifest.xml to add a second entrypoint into the subfolder'ed game, probably regenerating the .pri file and then hex-patching the game "data/"=>"dat2/". Works nicely with recent releases, but breaks when you try to launch archival versions, apparently due to some mismatch of some XAML file (embeeded in resources.pri). Possible to work around but I did not attempt that (a workaround likely requires game binary patch).
xAffan
commented
2 years ago
Hello, I'm considering officially supporting multi-instance some time later. However, you can already do this. Open up the folder with the game, then open the AppxManifest.xml in a text editor and see this MSDN article for details: https://docs.microsoft.com/en-us/windows/uwp/launch-resume/multi-instance-uwp#opt-in-to-multi-instance-behavior
As for multi-version multi-instance there's no easy way to do this, at least not one I could find. I know two approaches to do this: a) Multiple packages. Might require regenerating the .pri file (thanks to the other people for discovering that, including @abc-55 and @MisteFr). Breaks license and Xbox. No public way to work around either and there likely won't ever be (licensing can be bypassed with some effort, but afaik Xbox can not, someone would need to do some more research). b) Single package, multiple versions. Done by moving the second version into a subfolder inside the appx, moving the second version data folder to a four letter one inside the main app (like dat2/), updating the AppxManifest.xml to add a second entrypoint into the subfolder'ed game, probably regenerating the .pri file and then hex-patching the game "data/"=>"dat2/". Works nicely with recent releases, but breaks when you try to launch archival versions, apparently due to some mismatch of some XAML file (embeeded in resources.pri). Possible to work around but I did not attempt that (a workaround likely requires game binary patch).