Short answers, pulled from the story.
Fighter Maker is a series of game creation tools that lets players build custom fighters, design animations, and assign move sets. It spans PlayStation consoles, PlayStation 2, and Microsoft Windows, and divides into two branches: the 3D FM series and the 2D Fighter Maker series.
Skullomania, from Street Fighter EX, appears as a licensed character in the original Fighter Maker, complete with the character's original move list.
The UK band INTELLIGENTSIA composed the music for Fighter Maker and also created the in-game sound effects. One of the band's two members, MIRAI, is a playable character in the game.
2D Fighter Maker 95 was pirated and fan-translated into English, then released on the internet. It built a large following among dojin game makers and the M.U.G.E.N. community.
Enterbrain, the successor to ASCII, released 2D Fighter Maker 2nd. It revised much of the original engine to allow more options, expanded extension possibilities, and added a menu-based navigation system for greater clarity.
In 2019, Kadokawa exclusively licensed the 2D Fighter Maker 2nd engine to exA-Arcadia, which rebuilt it from scratch using hardware rendering. The arcade version added coin and credit handling, multiple language support, 16:9 widescreen, and an input latency of 0.3 frames, and is available only to exA-Arcadia developers.