The important part in the quotes is that they are somehow appropriate. Meaning they should not contain any violent content or anything that is promoting hate sexuality, copyright, advertisement etc. Basically all the stuff that makes people offended.
However the quotes do not necessarily need to be connected directly to the game, so you could also choose to make a quote about something you think is very interesting or about something you want people to think about - something that is smart or something that you learned the hard way or even a quote that you just really like or that was important to you at a point in the past. You could also decide to make a "gibberish" quote if that somehow makes sense let's say as a kind of riddle that others could find out by researching what it means. So basically there are a lot of ways to make your quote. We will be talking to you and help you if you need help. We are not interested in restricting you in any way but of course we also have to make sure that the quote won't harm the game and that the game doesn't get flooded by countless of nonsense posts.