Have a Franchise/Series as a Category.
I feel like there should be a general category for certain series. Such as Zelda, Mario, Megaman, RE, Digimon all under one catergory instead of individual games(unless they are a new). IGDB already implements this under what they call "Collections."
What do you think? People who play older titles but are a part of said series' community would be more in their line of audience. It's better than having them spread out in random places like Retro or Just Chatting. So instead of having massive communities around certain games, whether they are thriving or dying, you can have a continuous community around a certain series.