Spoilers of The Maiden's Rhapsody FFXI, I can't believe this, XI and XIV crystals

[Cilia]

While my knowledge of XI is cursory at best, and I've yet to do The Maiden's Rhapsody (partially owing to server maintenance, godsdammit)...

... there is no clear, concrete connection between any Final Fantasy worlds, except VII and X (more on that in a minute). There is the Void, an interdimensional rift that many characters use in crossover events or for cameos, such as Gilgamesh - the one we meet here is the same one from V who has appeared in numerous other titles. It's implied that Shantotto learned to traverse the Void, if only as a side-effect of some of her spells, and Bunhivelze sent Lightning through the Void and to Eorzea in preparation for becoming the "savior" he intended her to be.

As for "mothercrystals," some of my theories have been hinging on IX's position that all worlds possess a "mothercrystal," or crystal that sustains all life on the world; we go back in time to see the original Crystal be destroyed by Kuja, and... weirdness ensues. Point is, IX suggests there could be a crystal that controls the cycle of souls for every planet in the Final Fantasy multiverse, but whether this is true or not is up for debate (Hydaelyn is sentient, for one, and while the ones from IX likely possess sentience they never express it). I'd elaborate on that and how it relates to Hydaelyn, but that's not really the topic of discussion here.

Back to my original point, no two games share any concrete connection except VII and X - it was stated in an Ultimaina or something (and thus would not be widely-known outside Japan) that the two games are in the same universe, with VII being set in the distant, distant future of X. The connection comes from Shinra, the young scientist of the Gullwings in X-2 who proposes trying to harvest the energy of the Farplane. He and his descendants managed to do so and somehow made their way to VII's planet, which eventually saw the rise of Shinra, Inc., who used that tech to manufacture mako energy in a similar fashion. (Or so the story goes.)

[Lucke]

While my knowledge of XI is cursory at best, and I've yet to do The Maiden's Rhapsody (partially owing to server maintenance, godsdammit)...

... there is no clear, concrete connection between any Final Fantasy worlds, except VII and X.

Gonna play devil's advocate here for a sec. Each world in each game has a connection to the other worlds. Moogles, chocobos, magic spells and effects, and themes. But like you said, VII and X are the only pair that are the "same" world. Even though it's been debunked, I still believe Hydaelyn and Vana'diel are the same world like Spira and Planet. You can't have the same races just renamed and claim they're different worlds. Even though the Community Reps said otherwise, all the evidence says the worlds are related in some way.

[Fenral]

Back to my original point, no two games share any concrete connection except VII and X

It's technically a" side game," but Dissidia is set in the world of Final Fantasy I. Oh, the mind-screw that ensues when Garland appears on-screen with Chaos...

[Cilia]

Even though it's been debunked, I still believe Hydaelyn and Vana'diel are the same world like Spira and Planet. You can't have the same races just renamed and claim they're different worlds. Even though the Community Reps said otherwise, all the evidence says the worlds are related in some way.

Spira and VII's Planet (a.k.a. Gaia, not to be confused with IX's Gaia) are not the same planet. The theory is that Shinra made that tech to siphon energy from the Farplane, and his descendants became astronauts or whatever who eventually landed on VII's Planet and set up shop there. That's the difference between the Cetra (natives) and most people (ancient aliens... for real! Sort of!).

There are numerous similarities between XI and XIV (esp. XIV 1.0), mostly stemming from the influence of Hiromichi Tanaka, who originally directed both games and didn't seem keen on leaving XI behind. That said, there are differences between the races of the two games (there were absolutely zero female Galka as a facet of their existence, for one), and we now have the Au Ra, a completely original race. There is no hard evidence to suggest Vana'diel and Eorzea are related in any way - in fact, Shantotto noted during her cameo that she was not in Vana'diel, and Iroha is also aware she's no longer in her own world during The Maiden's Rhapsody. Beyond the original Five Races being near-practical carbon copies of XI's races (which, again, can likely be traced back to Tanaka's influence), there is nothing suggesting Eorzea / Hydaelyn has a stronger connection to Vana'diel than any other Final Fantasy world.

Believe what you will, but if you choose to believe in a falsehood over stated canon fact you're being willfully ignorant, and I... don't know what to say to that, to be honest.

It's technically a" side game," but Dissidia is set in the world of Final Fantasy I. Oh, the mind-screw that ensues when Garland appears on-screen with Chaos...

Technically, Dissidia (and 012) is set in World B, an alternate world from I's World A. Furthermore, as you so helpfully pointed out when I was discussing the Cloud of Darkness, all of the characters in those games are just really, really well-made manikins, so it's not too much of a stretch to believe Garland and Chaos are on the same field.

Dissidia Chaos and I Chaos aren't the same being anyway, despite their identical appearances.

[Fenral]

Furthermore, as you so helpfully pointed out when I was discussing the Cloud of Darkness, all of the characters in those games are just really, really well-made manikins, so it's not too much of a stretch to believe Garland and Chaos are on the same field.

Oh, of course. It's mind-screw for them, since they're the only two antagonists with that sort of link, and they're both aware of it but can't explain being in the same place at the same time.

Dissidia Chaos is... sad. That's really all I can say.

[Cilia]

Oh, of course. It's mind-screw for them, since they're the only two antagonists with that sort of link, and they're both aware of it but can't explain being in the same place at the same time.

Dissidia Chaos is... sad. That's really all I can say.

From what I remember, it's purely one-sided on Garland's part, since Dissidia Chaos isn't I Chaos and has absolutely no idea what he's talking about.

... but yeah, Dissidia Chaos is sad. Probably the most pitiable Final Fantasy villain ever.

[MaethusXion]

She is in our world permanently and will never get return back to Vana'diel, her new tale/story is in eorzea now. THAT there is how we are gonna get the samurai class, a class and teachings that will be passed down to us "The player" from another worldly character that comes from Vana'diel with skills unknown to our world.

She uses the Spear-like Naginata, so... TECHNICALLY she's a Lancer, not a Samurai...

[CyrilLucifer]

She uses the Spear-like Naginata, so... TECHNICALLY she's a Lancer, not a Samurai...

She's from Vana'diel, Samurai in Vana'diel use both Great Katana and Spears. She's definitely, absolutely a Samurai. especially given her relationship with a major character in XI who is the most powerful Samurai you encounter.

[Enkidoh]

She's from Vana'diel, Samurai in Vana'diel use both Great Katana and Spears. She's definitely, absolutely a Samurai. especially given her relationship with a major character in XI who is the most powerful Samurai you encounter.

Except lances were never SAM's best weapon in FFXI (usually SAM only ever bothered equipping one to abuse Penta Thrust), it was katana and great katana that what they were designed for. As for Iroha, she may be a SAM, but she's Vana'diel's version of a SAM, not Hydaelyn's (remember, Hydaelyn has a Far East too, and specifically, earlier in the storyline Yugiri and the Doman refugees hinted that there are ronin-like swordsmen in their homeland, meaning when SAM is eventually added to the game, it will be almost definitely a Doman who teaches the Job like NIN was, not a special npc from FFXI who happened to have FFXI's version of that Job.

And before you pass judgement, note how Shantotto was never referred to in FFXIV as anything but a 'sorceress' or 'witch', and not a BLM, because she is not an Eorzean BLM, but a Vana'dielian BLM. They may share certain traditional aspects and names, but their mechanics are completely different. But I digress...