So what is the best way to handle user accounts for a mobile game?
Clash Royal I noticed, for example, relies entirely on iOS Game Center and the equivalent on Android. There is no ‘cloud saved’ user account, it is bound to your iOS or Android account. This has the benefit that the user doesn’t need to login to Facebook or create user/pass to start playing the game and have their progress saved in a reliable manner.
I saw that the Amazon AWS Unity SDK had Cognito in it, is that any good?
Firebase Authentication works well. It includes email and social sign ins. Haven’t tried their Unity sdk yet but have used it in a bunch of other side projects. It really depends on the sort of user flow you want.
There’s still “cloud saved” data, the user just doesn’t have to explicitly log in - it’s done automatically based on their Game Center (or whatever) account ID. So I’d look for a service that implements equivalent functionality, such as…