Mega Man: The Sequel Wars Demo EX is a fan-made ROM hack for the Sega Genesis, focusing on the Mega Man series. It's likely a demonstration or early build of a larger project, showcasing a selection of levels and features.  Gameplay would probably involve classic Mega Man platforming, shooting, and boss battles. The 'EX' designation likely points to an expanded version of an earlier demo. Due to its fan-made nature, no specific company or organizer produced it, though individual developers would be responsible.

Mega Man: The Sequel Wars Demo EX

Mega Games 6 Vol. 3 (Europe)