Just finished implementing Amazon GameCircle support in one of Android our titles. The process was fairly straightforward and fairly well-documented at https://developer.amazon.com/sdk/gamecircle/documentation/unity-gamecircle-setup.html.
However, there were a few hiccups along the way. Here were a few key points that hopefully will save someone else time in their implementation:
- Don't download the Amazon GameCircle package from the Unity Asset Store. Because it doesn't work. Instead, download the latest Amazon SDK zip, extract, and do a Import Custom Asset on the Unity package contained in the archive.
- Don't use the short API code the Security profile shows. Do take the extra step to create the long API key with MD5. You'll have to extract the MD5 pattern from your apps keystore to generate the API key on the Amazon website, then copy the generated API key from the Amazon developer console. See https://developer.amazon.com/sdk/gamecircle/documentation/gamecircle-config.html#Section5 for more details.
- Make sure the Android app manifest is renamed and correct. The Android application manifest example file has a lengthy name of "GameCircleExampleApplicationManifest.xml" or something. Which won't be found. It'll have to be renamed to AndroidManifest.xml, or else your app's permission settings will be wrong, and you'll be digging out adb logcat to understand why your application stops on a NETWORK_STATE_ACCESS exception or similar.