Pigsy is a name you might already be familiar with if you're a Mega Drive / Genesis fan and you like fan-made ports. He's currently working on bringing Castlevania: Symphony of the Night to Sega's 16-bit console but also has other projects on the go – including a conversion of GG Shinobi.
Pigsy has shared a new development update for the port, showing the process of manually "upscaling" the Game Gear visuals for the higher resolution of the Genesis / Mega Drive.
He also explains how he's adding in new elements, too, such as parallax scrolling, which was absent in the original game.
The video is well worth your time, as it goes into the complexities of performing such a port from one system to another.
Other big-name homebrew ports coming to the Mega Drive include Final Fight, R-Type, Splatterhouse and Vigilante.