Run Android 6 (Marshmallow) via an emulator on your PC (e.g., Bluestacks) and install Mini Militia 6b there. Then play with friends via emulated LAN.
While you can download via the website, Uptodown also offers an app store client that manages older versions for you, making updates (or downgrades) seamless. Mini Militia 6b Download Uptodown
A: No. They are separate apps with different package names and signatures. However, you cannot have both installed simultaneously on some devices (signature conflict). Uninstall the modern version first. Run Android 6 (Marshmallow) via an emulator on your PC (e