There is a perfect way to continue the world of master detectives. The key is in the title:
Master detectives archives
Basically be the cases the wdo has achieved in their library. Being rain code the name of the case.
Each game would be a different case.
This would allow the games to not need to follow a strict timeline of events. Past cases or future ones, new locations, new characters or developing already existing ones ( like the Amateurs express detectives or the NDA detectives rookie days)
Maybe one could be the WDOs beginnings, maybe two games could occurre in the same location but during different periods.
I'm not saying that they should close the rain code storyline, but maybe expanding the world could allow for a better way to continue it.
Maybe during one of the games Yuma helps out the protagonist but they aren't told who he is until after he leaves, never or maybe they run in with one of the NDA detectives and they tell them.
I think Rain code is a good as stan alone. I think they might not continue the series because of the whole "trapped murders"/ "close speace misterys" isn't as easy to continue in an open world.
But it doesn't necessarily mean they have to be literally trapped. They could simply stay there because of determination.
There is also the Death gods,Shinigami confirmed that there are more death gods apart from her. Are there other death gods that help out detectives? Can you offer something else, other than your memories, make a contract? Are all death gods bound to a book? Does it have to be a book?
I've been thinking about this ever since I saw the trailer for rain code. I just think this is a game that has a lot of potential.

















