Most Final Fantasy games have quite a lot of ways to be expressed:
Final Fantasy IX (Name, Roman Numeral)
Final Fantasy 9 (Name, Arabic Numeral)
FF IX (Shortname, Arabic Numeral)
FF 9 (Shortname, Arabic Numeral)
As per Should we standardize our tag formatting regarding Arabic vs. Roman numerals?, it appears that this (and other) series of Games have been dealt with, when it comes to their name.
However one particular thing that stands out is that you can't search for Final Fantasy games by their Shortname (FF).
However you can do so with Defense of the Ancients (DoTA), Left For Dead L4D.
Is there any particular reason why there aren't "FF9", "FF7", etc.. tags as synonyms?