We propose a technique to implement multi-user game environment based on Android platform using Unity™ without relying on conventional Unity network plug-ins, which are often on a commercial basis. Since our proposed method utilize own native Android™ codes based on the Android SDK to facilitate network communication among game players, the proposed technique provides with higher flexibility and more transparency than general Unity network plug-ins, which are almost impossible to customize. One of our main ideas for implementation is to deploy the Unity binary code and the native Android network implementation as a layer respectively on the Android platform. Based on our method, we have implemented a mobile multi-user game on Android devices. Also, we discuss our technique according to the Unity’s design philosophy, “one code for multi-platforms.”