This page explains how to get and install Karaoke Mugené Mugen.
NOTE : Once installed, Karaoke Mugen does not need any internet connection, except for features like url shortener or online accounts.
Download and install Karaoke Mugen
Binaries for Windows and macOS are available. They are portable : you don't have anything else to do to install and use them.
Uncompress the .zip archive in a folder of your choice where there's a lot of disk space available.
Once done, you can go to the getting started section!
The version of mpv provided by the Ubuntu repositories is obsolete, and not compatible with Karaoke Mugen.
You must thus install another version. mpv's official site provides several ways to install Karaoke Mugen, but the simplest is for Ubuntu and its derivatives to use the following PPA :
sudo add-apt-repository ppa:mc3man/mpv-tests sudo apt-get update sudo apt-get install mpv
Check out mpv's website for more info.
If you use macOS Catalina you'll need to disable SIP/Gatekeeper in order to run Karaoke Mugen properly.
The required mpv version for macOS is 0.25, but to make fullscreen work better, you'll need version 0.27. Install it through your preferred method (macPorts, Homebrew, binaries, etc.)
A version for Raspberry Pi is available through the Mugen Pi Project