All Instant play games must support automatic sign-in using Google Play Games Services. Use Google Play Games Services to provide a consistent player ID that you can use to restore saved progress from the cloud.
Size impact of the library
The size impact of the Google Play Games Services library depends on whether the game engine runs on Unity, Java, or Native.
Java
The size impact is minimal because ProGuard is informed about which classes are used.
Unity
You can integrate the game save feature into your Unity game using the official Google Play Game Services plugin. The size impact is around 200 KB if you use the ProGuard recommendations.
Native
You can integrate the game save feature with a game built on the Android NDK using the Native Play Games Services SDK.
Use the general ProGuard configuration below to strip out most of the Java code included by the library. You can implement Play Games Services sign-in and game save with this configuration, while only adding about 250 KB to the APK.
# The native PGS library wraps the Java PGS SDK using reflection.
-dontobfuscate
-keeppackagenames
# Needed for callbacks.
-keepclasseswithmembernames,includedescriptorclasses class * {
native <methods>;
}
# Needed for helper libraries.
-keep class com.google.example.games.juihelper.** {
public protected *;
}
-keep class com.sample.helper.** {
public protected *;
}
# Needed for GoogleApiClient and auth stuff.
-keep class com.google.android.gms.common.api.** {
public protected *;
}
# Keep all of the "nearby" library, which is needed by the native PGS library
# at runtime (though deprecated).
-keep class com.google.android.gms.nearby.** {
public protected *;
}
# Keep all of the public PGS APIs.
-keep class com.google.android.gms.games.** {
public protected *;
}