What are you asking?
If you're asking why Necrozma doesn't have a game based around it, similarly to how Rayquaza and Giratina had a game based around them, it's probably because Solgaleo, Lunala, and Necrozma don't really form a trio, as pretty much the only way Solgaleo and Lunala are related to Necrozma is because of Ultra Sun/Ultra Moon. Also, there have only been three games based off of a third legendary Pokemon, Crystal, Emerald, and Platinum. It's been eight years since Platinum was released, so I think that it's not unlikely that there won't be any more Pokemon games with a third version. I'd also like to point out that, even if Necrozma did get its own game, "Eclipse" would be a pretty bad name for it.