Hey i'm one of the developers of mod.io. Every part of the service is entirely optional, so if you take a look at the 0 A.D. implementation they completely bypass our authentication system and manage a users mod collection in-game themselves.
This means some features like "subscribing to auto install" don't work, but for them they want everything to occur in-game which is fine by us.
This means some features like "subscribing to auto install" don't work, but for them they want everything to occur in-game which is fine by us.