You can now easily package Android games using Castle Game Engine to the AAB format (instead of APK). New Build Tool command-line options allow to execute:

• castle-engine package --target=android --package-format=android-app-bundle

  Will package to the new AAB format.

• castle-engine package --target=android --package-format=android-apk

  Will package to the traditional APK format. The --package-format=android-apk is right now the default behavior, equivalent to also using --package-format=default on Android — time will tell whether we will change this default to AAB.

Why the new Android package format?

Starting August 2021 (next month!) all new apps published on Google Play Store are required to be uploaded in Android App Bundle (AAB) format and from November 2021 all updates to existing apps at Google Play Store will be required to use AAB format. Also, uploading apps in AAB format overcomes Google Play Store 100 MB limitation on a project build, which is especially important for games, as different assets can take up a lot of space and reducing their quality is not always a good option.

Note that we still support packaging to regular Android Packages (APK) that can be instantly installed to an Android device and it still remains a default packaging format for Android platform, as it is very convenient for development purposes or for distribution through alternative to Play Store platforms, e.g. uploading to itch.io.

Android App Bundle (AAB) is a collection of prebuilt resources targeted for different user devices (such as Android version, CPU architecture, Screen resolution). Play Store then automatically generates an APK based on user configuration. Note that it also means that AAB package cannot be directly installed on a mobile device/emulator and therefore for debugging and internal testing APK is still a necessary format.