CODEX
Celestia
"The Voice"
Moogle
Chocobo
Sabotender
A parallel dimension - some say it's situated in the middle of infinity, while others say it's a dream within a dream. This surreal omniverse is the generic stage where you will begin your quest in search of your identity, your past; here's where players will build a miniworld to develop their characters beyond the known canon stories within its astronomic bubble.
"The Voice"
A mysterious entity that you cannot see, only hear in your mind - at times it helps to guide you through this foreign land you are exploring, but whether or not it has an agenda for doing so, only time will tell...
Moogle
If hearing voices in your head isn't weird enough, how about getting another guide - this time a physical one, but in the form of...uh, a floating plush toy? Well, the Moogle (or more affectionately known as "Moglin" or simply "Mog") will be your first traveling companion in this surreal land, but even so you can barely drop your guard - this little one just doesn't make you feel at ease at all with its apparent clumsiness, made worse by its overly helpful nature. No one knows where they come from; they are already your side when you wake up...kupo.
Chocobo
This wild and flashy avian may not be able to fly given their rather large body, but their powerful legs allow them to sprint across the lands of Celestia - there isn't any place where this bird-like creature has yet to set foot on. They can be a great way to ease ground transportation, but only if you have what it takes to tame this free-spirited beast to bend its will to do your bidding.
Sabotender
More commonly known as "Cactuar" in the English games, these cactus-like creatures may seem cute (or even dumb-looking, depending on how you view them) but they are dangerous for their signature "1000 Needles" attack, easily inflicting heavy damage on anyone. However, in Celestia they have a mischievous touch: using their quickness as a weapon, these little flora prey on unsuspecting travelers, looting them for anything they deem valuable. If you're able to stumble upon a Sabotender's lair, the amount of stolen treasures hidden within would easily turn on your instinctive greed, but that is if you can get past the guarding Jumbotenders (a.k.a. "Gigantuar") first...
Orbis
Astra
In VII, it's known as "materia"; in Spira, they call it the "sphere"; in the Fabula universe, it becomes "phantoma" - the orbis functions the same way as all of those: a type of elemental substance abundant in Celestia, which you can collect for combat uses, to refine your equipment, among many other things.
Astra
Known as "Summons" in most instances - including other names such as "Eidolons" and "Espers" - the Astras are shadowy warlords that reside in the void between the miniworlds (you can see it as a separate plane). They usually lay dormant within this space; you can call them forth via a Summoning Ritual by offering something of equal value to borrow a portion of their power, albeit temporary before they leave and go back to their deep slumber once more. No one knows the true form of the Astras, for they can easily shift their appearance into an image that can be comprehended by the person who sets sight on them.
Here's where you can check and/or keep track of the character's locations (read: the terrain they currently arrive at) to give you some insight to help you with miniworld crossovers.