From what we've been able to gather, Shadow Gangs Zero originally started life as the "16-bit" port of Shadow Gangs for the Neo Geo AES & MVS but has since grown into a slightly more ambitious project, featuring altered level layouts, additional stages, more animation frames, and a redone soundtrack.
It was initially announced back in January 2024 on Twitter and has since been subject to various updates across social media — the latest of which concerns the reveal of a Sega Mega Drive / Genesis version.
The game, much like the original, will see players taking control of a character named Dan, who is the current master of the ninja order, as they embark on a perilous quest to rescue their family from the Shadow Force crime organisation. However, JKM Corp promises a "different [experience] for people who finished SG1" that is much "longer" than the original.
There's no footage of the game available yet from what we can tell, but JKM Corp has been posting some of its progress on the Neo Geo version online.
JKM Corp ultimately plans to launch a Kickstarter in the future to fund all of these projects, with the developer previously giving a tentative release date of 2025. A sequel Shadow Gangs II is also planned for the future, but the development of that game won't begin until work on Shadow Gangs Zero is completed.