Sonic UMGZ is likely a fan-made game or ROM hack for the Sega Genesis. The 'UMGZ' part of the title suggests it might be a large-scale project or a compilation of various levels and features. It might take inspiration from various Sonic games or create entirely new content. The core gameplay should probably stick to the platforming genre of the original games. The original Sonic game was developed by Sega and is still a recognizable title today.

Sonic UMGZ

Sonic the Hedgehog: Isle of Magnetic Artifacts