While FFXIV definitely does have its own multiverse in the story, I think that's split from say, the great FF multiverse containing other games' worlds.
Going strictly on what 3.4 and the lore book provide on creation myths, Hydaelyn (the planet) is one of 14 worlds, being the "source" which then got a bunch of mirrored reflections. Each of those reflections had their own histories (however similar) and then plot happened.
If we take old seasonal events seriously and literally, Shantotto from FFXI does use some powerful form of magic to travel across the void to visit Eorzea. But it seemed much more like a fluke or an experiment than something intentional. The same for the Lightning event and the Maiden's Rhapsody event).
So while there is certainly some form of possibility in linking these worlds, the Warriors of Darkness had to pay quite the price just to hop from a relatively "local" world. And gods (or Tarutarus with the power of gods?) have had to be the means of bringing in other characters for these usually short-lived cameo events.
I'd ultimately ask what it would bring to your RP beyond people/IC characters/NPCs thinking your character was insane. ...let alone how they'd manage to communicate with a world of people speaking some language that isn't theirs. (Not all Echo-enabled people got the free translation of intent/meaning feature. And it doesn't handle reading.)
Going strictly on what 3.4 and the lore book provide on creation myths, Hydaelyn (the planet) is one of 14 worlds, being the "source" which then got a bunch of mirrored reflections. Each of those reflections had their own histories (however similar) and then plot happened.
If we take old seasonal events seriously and literally, Shantotto from FFXI does use some powerful form of magic to travel across the void to visit Eorzea. But it seemed much more like a fluke or an experiment than something intentional. The same for the Lightning event and the Maiden's Rhapsody event).
So while there is certainly some form of possibility in linking these worlds, the Warriors of Darkness had to pay quite the price just to hop from a relatively "local" world. And gods (or Tarutarus with the power of gods?) have had to be the means of bringing in other characters for these usually short-lived cameo events.
I'd ultimately ask what it would bring to your RP beyond people/IC characters/NPCs thinking your character was insane. ...let alone how they'd manage to communicate with a world of people speaking some language that isn't theirs. (Not all Echo-enabled people got the free translation of intent/meaning feature. And it doesn't handle reading.)