Originally Posted by Memoria
I always kept thinking that FFIV and FFIX had similarities up the wazoo, but I once wrote a fanfic crossover FFVII and IX, where they were on the same world, just different times, and I didn't even know that VII's world was called Gaia. Though I do believe they aren't on that world. Sad, but true.
Simularities in all games include a magical girl heroine and a badass guy, plus a hero with some mental problems, a few none human characters -or at least someone not of the same main race on that planet, lots of battles, magic, summons, and... of course, the rabid fans.