MUGEN 1.1 is a popular, freeware 2D fighting game engine originally developed by Elecbyte. It allows players and creators to build their own fighting games, design custom stages, and add characters—often bringing together fighters from entirely different franchises like Street Fighter, The King of Fighters, and various anime.
The 1.1 Beta version is highly regarded by the fighting game community for several key upgrades over its predecessor, MUGEN 1.0

• True Color and Translucency: Unlike older versions limited to 256 colors, 1.1 supports 24-bit full color (with an 8-bit alpha channel), allowing for much richer stages, character sprites, and translucent spell effects.
• Dynamic Camera Zooming: It introduced built-in, cinematic camera zooming that tracks characters dynamically during fights or dramatic special moves.
• Expanded Developer Tools: It added direct support for in-engine rotation/scaling and hardware-accelerated rendering.