I was digging into the game files on Android and discovered that Battle Gems is created by...Unity.
Yeah, Unity. AE most likely dumped thousands of dollars on Unity. It costs thousands of dollars to put in in-app purchases and to take off the Unity logo from the loading screen. Though I'm surprised. From the way AE initially described it, I thought AE would use a huge multiplatform engine that's more for 2D, such as Cocos 2D-X or Corona SDK. Unity can be used for 2D games, but a lot of the top mobile games were made with Cocos 2DX.
Unless I'm wrong. The only reason I think this is because in the com.battleon.aqbattlegems, there is a lib folder, in which is a file named libunity.so. After a brief Google Search libunity.so is, in fact, one of the main files of the Unity Engine.