The King of Fighters Zillion is a MUGEN project that gathers dozens of characters from the classic KOF series, adding more modern gameplay and a sleek UI. Development started in the MUGEN CHINA forums around 2008 and slowly progressed until the forum's demise in 2012. Although the game was mostly complete (only lacking a few characters), released and open-sourced, the project is considered defunct as the original developer team has yet to reunite to resume development. Several fan-made continuations of the project exist, such as "KOFZ Plus", "KOFZ Ultimate" and "KOFZ2"; the most acclaimed being "Rayzo's KOF Zillion 4.1 Widescreen", which aims for fixes, stability, widescreen support, characters' alternate versions, and overall improved aesthetic values.