Could I ask a question, for instance, about the Super Mario Bros.-based cartoons or Dishonored books here?
If your question is specifically about books and/or cartoons of a game you shouldn't ask here.
We are primarily focused on playing games and while there are certainly some people on the site who are familiar with the "extended universe" of the games they're playing it's not really our expertise.
We can help with lore related questions if the information is available in-game.
If you have questions about a series or movie about a game you could check out movies.se.
Just make sure to read their FAQ before posting a question but those things should be on-topic.
Again as I've said there are a lot of people interested in the extended universe of games on arqade and fortunately we do have a chatroom where we can discuss things like that. So if you just want to chat and discuss some topics about game related media feel free to join us in The Bridge or you could even create your own chatroom.