Some things to keep in mind regarding the Android port:

• As with the other ports of the Sonic 3 A.I.R., you need to deliver the Sonic 3 & Knuckles Steam ROM yourself, and need a PC or Mac for that. See installation instructions below.
• Menus can only be controlled by using the virtual touch gamepad (or an external game controller, that works as well). In other words, you can't tap buttons there directly, but need to select them like with a gamepad.
• Startup loading times can be quite long. A black screen of 15 seconds or even more before the disclaimer is normal on slower Android devices.
• Game performance can be an issue on low-end devices - you might not reach constant 60 frames per second. If possible, stay with the OpenGL hardware renderer (that's the default) and only choose another renderer if you encounter graphics issues.
• Mods are supported, but you need to install them using the File Browser in the System tab of the Options menu.

How to install: (requires a PC or Mac!)

• Step 1: Find the ROM
  First make sure you have the ROM from the Sonic 3 & Knuckles Steam version ready on your PC or Mac.
  To find the ROM, open your Steam Library, make sure Sonic 3 & Knuckles is installed, then right-click "SEGA Mega Drive & Genesis Classics" and select "Properties...". A new menu will pop up, navigate to "Local Files" there and click the "Browse" button in the upper right. This will take you to the installation folder of the SEGA Classics, where you can find the game ROMs inside the sub-folder named "uncompressed ROMs". Select the file "Sonic_Knuckles_wSonic3.bin" there - that's the Sonic 3 & Knuckles ROM.
  Bad news as of May 2022: Unfortunately, the game is delisted on Steam now, so the go-to way to get the ROM is gone... You might want to check out these legal alternatives .


• Step 2: Copy the ROM to your Android
  Connect your Android device to your PC / Mac with a USB cable, and access its file system. Or alternatively, you can use your Google Account to transfer the file. Both is described here .
  It does not matter where exactly you copy the ROM file, it could be e.g. the Downloads folder.


• Step 3: Install the game APK
  Open this page on your Android device, and download the APK:
  • Stable Update v26.03.28.0 (recommended)
  • Stable Update v24.02.02.1 (previous stable update)
  When the download has finished, launch the APK (most browsers will ask you if you want to install the APK anyway).
  It's possible you get a warning about installing from an untrusted source. If so, follow the on-screen instructions to make such installations are allowed.


• Step 4: Start the game
  On first start, you will get a warning that the Steam ROM is needed and will be asked to select the game ROM. Tap "OK" and use the file selection dialog to find the ROM you previously copied to your device (or to your Google Drive, if you went for that option). After file selection, the game should load now. Congratulations!


• If the ROM can't be selected: Launch the ROM file itself
  In some cases, the ROM file does not show up in the file selection dialog, even though you have navigated to the correct location. If that happens, try this alternative method:
  Open a file management app, e.g. the (often pre-installed) app called "Files", or any other ("FX", "Samsung My Files", "ES File Explorer", etc.). Or in case you‘re using Google Drive fortranferring the ROM, use the Google Drive app.Navigate to where you stored the ROM, and select to open / launch the file. If the app supports it, this should pass the ROM to Sonic 3 A.I.R. or give you the option to do so. Note that this method works best while Sonic 3 A.I.R. itself is not running in the background.

Need more information?
Have a look at the Manual PDF - it explains the installation of the game (incl. updating from a previous version), installation of mods, and more.