Everything except making a store people wanted to use? Ethan Evans, who was previously Vice President of Prime Gaming at Amazon, has a short retrospective of trying to take on Steam.
Or just let people download installers like GOG does, that way you don’t need to make and maintain a game manager (which GOG does anyway, for some reason).
I want and use Galaxy on Windows, and support for things like achievements, chat and cloud saves are a big deal. But this is also true. You can use stuff like Launchbox or Heroic on Linux to do the same thing even without a specific API if you allow third party installer DRM-free downloads.
Or just let people download installers like GOG does, that way you don’t need to make and maintain a game manager (which GOG does anyway, for some reason).
I want and use Galaxy on Windows, and support for things like achievements, chat and cloud saves are a big deal. But this is also true. You can use stuff like Launchbox or Heroic on Linux to do the same thing even without a specific API if you allow third party installer DRM-free downloads.