Invincible Iron Man Gagaga-In is a cancelled “80’s giant robot fighting action game” for the Virtual Boy, that had been in development by Hudson Soft and the planning and contract development group Eighting. It was planned to release in Japan roughly a year after the system launch.
The game has never been officially announced, but images of a design document and an EP-ROM cartridge containing a sample build have been shared in 2018 by an (allegedly female) former Hudson employee.
They have even uploaded a 58-second video of the game in action to NicoNico in 2013, but unfortunartely, the video was quickly deleted on the same day by request of “stakeholders of the developer”. The video description praised the game to be “very responsive with well-developed techniques” and being “a lot of fun”. It also mentioned that the music was a placeholder, taken from Panic Bomber.