I could not find the information anywhere, so I was wondering whether there is any restriction on the kinds of medium whose works can be discussed here? Books, TV, Movies seem to be fair game but what about other mediums like maybe board games/anime etc.?
Expect most questions to be about books, movies and TV shows, because that's what most people see/watch. But questions about radio broadcasts, comics, cartoons/anime, plays, paintings, interpretative dance, or whatever medium suits your fancy are just as welcome.
When it comes to games, there are other Stack Exchange sites. Questions about the SF-nal aspects of a game are welcome here, but questions about the gameplay are off-topic on this site and should be asked on the relevant game-related site instead (as per this Meta post):
I believe as long as you are referring to the Sci-Fi or Fantasy content in a medium, whatever that medium maybe, then it is on-topic.