So Satoshi Sakai made a blog post detailing the setting of PSO2 as well as explaining some other bits. You can read a fully translated version on Bumped.org here.
So where is Phantasy Star Online 2 set?
In the Gurhal system? No, you’re dumb.
On Ragol? No, a bit less dumb though given the title of the game..
On Algo- yeah not gonna go through the list.
The answer is space. Yes. Space. As it turns out, the Oracle, that great big tree like spaceship, consists of a fleet of ships that travel to many planets. Now, given that they seemed to struggle to come up with enough content to cover just 3 planets in Phantasy Star Uiverse, I’m not going hold up my hopes that they’ll create meaningful content for what could be a considerably larger number of worlds. On the other hand, a setup like this allows them to basically add whatever worlds they feel like, keeping things very open for future expansions. It’s also somewhat fitting, seeing as we’re also going back to an explorer theme as opposed to what we had in Phantasy Star Universe, where all 3 worlds were already well explored before the player arrived.
Your arch enemies this time are the “Darkers”. Same old. Although they appear to be life forms all their own rather than corrupted life forms, but corruption as a theme is bound to be in there somewhere.
Oh, yeah, that giant-tree ship? You’re not allowed on it. It is a holy place or something. You’re too filthy. You filthy bastard. Instead, as a member of the Arks you will live on the Arks Ship.
Oh yeah and the planet full of green that you saw is called planet Naberius. Data mining, or cheating depending on who you ask, revealed 7 more planets. But hey, given the setting of the game they could add more without any explanation necessary.
Naberius has these cute little things on it, called Nav Rappies. I don’t know about you but I cant wait to slice them up and use their bodyparts to make new weapons.