Downloading a "pre-packaged" APK that includes the game data is considered piracy. The safest way is to use the Official Decompilation GitHub and your own legally owned files.
Here are some tips and tricks to help you get the most out of Sonic CD Restored on Android:
Note: For the best experience, a clip-on Bluetooth controller or a mobile gaming cradle (like a Razer Kishi or Backbone) is highly recommended to handle the fast-paced platforming. Why Choose the Restored APK Over the Official Port?