Show a toggable list of mods of the in the main game page.
A list of mods could be shown as toggable to not mess with the layout of the page, since some games have an extensive mod library (I'm looking at you Super Mario World and Super Mario 64).
It would be better a "This game is unofficial" label.
It concerns most specifically games that have a huge amount of fan games, such as Mario or Pokémon franchises, in order to don't mix themself with the real games. But having a special section for them can also be useful for API users, in order to filter them if not needed. Could be added under the "This game is a version." section on the edit page, as "This game is a fan game."