Originally Posted by
Keyln
I think you have a fundamental misunderstanding of the Final Fantasy cosmology. Each game of the Final Fantasy series takes place not in an alternate universe, or in an extra-dimensional plane, but on its own planet in the same universe (or more likely, galaxy). Travel between these worlds is very difficult, but possible, and it has been done. This has been accomplished by travelling in an asteroid (V, IV: After Years), or travelling through the void (V, VIII, IX, XII). This is not to say that alternate timelines don't exist (IX: Wings of the Goddess, XIII-2), or that alternate worlds exist (IX, XI: Abyssea, Dissidia), but for the most part, the default is that each game in the Final Fantasy series takes place on a different planet with various themes (although it does bring up questions about how humans have managed to appear on these different worlds, or how chocobos appeared as well, although there is a bit more evolutionary diversity than in humans, but I digress...). Atomos also seems to have the power to transverse worlds (V, XI: Wings of the Goddess, XI: Abyssea, XIV), as it has the power to transverse dimensions and time. The Void also seems to be a bit of a mystery at this point, but it appears to be an extra-dimensional system through which one can travel. It's not unlike wormholes which connect to distant points in space.