Blender version selector automatically picks the correct Blender version when you double-click a .blend file based on which version of Blender the file was last saved in!
Essentially this is useful for anyone that frequently use different versions of Blender on the same computer & for different projects. For my particular usecase I originally developed this as I use one Blender version for my Armory 3D projects and another more recent version for other projects as I tend to love using alpha/beta releases (of which Armory typically doesnt support).
If the version selector fails to find a version on your system that matches the version of which the blend file was last saved in, it will prompt you which version you wanna use instead
For the time being its Windows only, though it might be relatively easy to port considering the entire application is under 300 lines of code.