Go to Settings > Security and check the box to allow installation of apps from "Unknown Sources."
Since Summertime Saga features adult content, it is not available on the Google Play Store. You must download the APK file directly from official sources and install it manually. Prerequisites: Android device running Android 5.0 or higher. At least 1-2 GB of free storage space. "Unknown Sources" enabled in your settings. Installation Steps: Summertime Saga 0.20.16 APK For Android
Open the downloaded APK file and click "Install." Go to Settings > Security and check the