M.U.G.E.N (AKA: Mugen, MUGEN, 無限) is a discontinued but still very active free 2D fighting game engine with many customizable components. It was developed by Elecbyte, first released in 1999 (for DOS). In 2009, MUGEN 1.0 was released, and in 2013, MUGEN 1.1 came out.

Mega Mario (also called New Super Mario) is a fan-made clone/Dojin edition inspired by the classic Super Mario Bros. and Mario Forever. It was written in C++ using SDL, equipped with brand new levels, fluent and smooth graphics as well as clearer user interface. Below you can get its full version with high quality background music.