I think the usual stuff about not insulting other users, for example. But I am sure that more rules will come to mind when we'll write the draft.
Actually one has come to mind just as I was writing this. Categories: we shouldn't allow users to create random categories. If someone thinks a category should be added he must ask an admin. I also think we have redundant categories that need to be cleaned up. For example, do we really need a category for each studio? Someone also made a 2014 movies category and I deleted it. Surely we don't want more than one hundred categories one for each year starting with 1895, right?
I also think that we must not allow pages about movies that are not yet released, it's just preposterous and adds potential pages that needs to be deleted for no reason at all.
Also think about a rule that quickly explains how to write a page, like in the two games wikias.
What we don't want is rules created after what the anon did. Things like "do not write pages about memes or videogames" were casually discussed in the blog but I strongly advise to not state this in the rules. That vandal must not dictate how we must rule our wikia. That preposterous behaviour can be easily punished as vandalism and that's all.
Finally we must write down what will earn a block. I can't think of something else, for now.