San Andreas Unity
Open source reimplementation of GTA San Andreas game engine in Unity
... and IL2CPP scripting backends, so it can be built for any platform that Unity supports, provided that you can copy PC version of GTASA to target device. Game fully works in multiplayer. You can start the game as dedicated server, as a host (server & client at the same time), or you can connect to a server. This works on all supported platforms, which means you can start a host even on Android device.