As Unity 3D is (mostly) not open source, Google must be working directly with the developers of Unity on the Android Game SDK.

Key benefits of Xsolla SDK for Unity include: Drop-in Unity Integration: Seamlessly integrates Payments, Web Shop, and other direct-to-consumer solutions into Unity projects with broad version ...

To demonstrate just how easy game development with Unity is, I’m going to show you how to make your first Android game in just 7 minutes. No – I’m not going to explain how to do it in 7 minutes.