Not sure if I understand your question, but usually new games will be released at different times on Stadia. They've added a lot of new games over the last months/year, so I have no doubt we'll see some new ones coming soon as well.
If you wait for a specific game, it's probably best if you get in contact with the developer to check if that game is planned for Stadia. Otherwise if you're just interested which new games in general are released on Stadia, you can also check out the Stadia community blog as new games will also be announced that way.
