I need some unique Google Play ID to identify a player cross-device. If the same user enters my app using a different Android device, I need to know that it’s the same user so I can load his progress from my database.
Docs say I should use Google Play Game Services to fetch the PlayerID. According to the docs, this ID is always the same for the user using the particular app. The reality is different. It’s not the same. It depends on the Android version and whatnot, so if a user buys a new smartphone, he can lose the entire progress as I could not identify him anymore. This issue has been discussed many times.
However, there must be a way to identify the user. What’s the bulletproof common approach for this?