Ten Things you need to know about Ortho
1. The planet has been tamed, for better or worse.
Ortho is not a planet where there are hordes of orcs about to press their barbarian host over the gates to destroy Civilization As We Know ItTM nor is it a place where fickle gods are going to curse entire cities. It seems like a planet that has been largely brought to stability and prosperity by its current government.
Adventurers will instead be focused on protecting the planet from evils from outside of dimension trying to get in, political intrigue, pursuing evil criminals, opposing the excessive elements of the law, and possibly working to overthrow the world government if they are Chaos-inclined.
2. Law vs. Chaos is a conflict that most mistake for Good vs. Evil
The average person on the planet Ortho respects the law. The government has ruthlessly suppressed tales of merry rogues and criminals are depicted without a hint of the glamor that they enjoy in other settings. The idea of freedom exists on the Planet Ortho but a lot of people don't seem to weigh it as heavily as they do obedience or stability. Frankly, most trust the world government whether they should or not.
Those with Chaotic alignments and dispositions will often find the planet stifling or even dangerous. Those who break the law on Ortho run the risk of being hunted like the worst sort of villains since few can imagine a difference between a criminal and an evil doer.
3. Elves are extinct
Perhaps the greatest evidence of the troubles of Ortho is the fact that an enitre player character race has been removed from the face of the planet. Elves were long ago wiped out by the war against Chaos that was Ortho's darkest hour. Half-Elves are, likewise, no longer available for play. Instead, Ortho is a world that has great populations of Aasimar and Tieflings to replace them.
With your Dungeonmaster's permission, it might be possible to play a throwback to Elvish blood.
4. The Orthorian Central Authority is neither Good nor Evil
The world government of Ortho can be both protagonist and antagonist to Player Characters. An all pervasive and powerful political force, the OCA is absolutely everywhere in the setting. They are filled with a mixture of caring statesmen and heinous fascists that both want to direct the course of the government's future. PCs might well ally with them one day only to oppose them on another.
5. The Populous is a Religious One
The role of the gods is linked to the power of the state and the two feed off one another. The Lords of Order are a group that almost every person in Ortho worships. While there are demon cults and religious dissenters, most of the populous has accepted the religion of the OCA. Like the bureaucracy, the priests of this faith are mixture of good and evil. Both types are equally respected so long as they continue the service of law.
6. The Planes are strongly tied to Ortho
The populous of Ortho have successfully colonized other worlds thanks to the planar gates that they've mastered. Furthermore, their most immediate concerns are incursions from the Outer Planes as opposed to internal dissent. They have sent armies into the Abyss in order to tame it, as foolish a decision as that was. By their very desire to master the planes around them, Ortho has drawn a lot of divine (and infernal) attention to itself.
7. Ortho is neither a Utopia or Dystopia but has elements of both
Ortho has Re-education camps, Bureaucrats that deal with Devils, and a militaristic culture that places the majority of decision making in the hands of those who wield swords. Simultaneously, Ortho is also a planet with an underclass that is well cared for and individuals who continue to fight for justice. It will be up to PCs and individuals like them to determine whether Ortho falls on one side or the other.
8. The average Orthoian is educated but ignorant at the same time
Ortho is a planet where schooling has been made available to much of the populous. However, that schooling has been controlled so that the education of most is a product of the State. Thus, most Orthoians are no less intelligent than other campaign setting individuals but their knowledge is almost always influenced by what they've been told by the OCA. This can lead to wildly inaccurate views on the nature of the gods, planes, and certain races.
9. Specism is less important than one's devotion to Order
On Ortho; Dwarves merilly work beside Orcs, Humans, Beholders, and Hobgoblins. Any race with the "Lawful" descriptor in the Monstrous Manual is likely to be found in abundance on Ortho. Simultaneously, races with the Chaotic descriptor (Orcs and Lycanthropes aside) are much more likely to be a persecuted minority or underclass on the planet. This is one of the driving conflicts of the setting.
10. Ortho's Empire is expansionist
Even if you're not interested in role-playing a native of Ortho, the planet is interesting in spreading the reach of harmony across the universe. They have already managed to dominate more than one planet with their colonies. While they are not actively seeking other worlds to dominate, it may only be a short time before other Prime Material Worlds find the people of Ortho coming to 'restore order.'
Pretty good, although somehow I doubt the humans would work well with the Illithids. What with the brain sucking and all. I sort of saw the Illithids as being one of the races the Harmonium has been hunting, but who have retreated so deep underground and are so well hidden that they are nearly impossible to uproot. If we do have them living out in the light of day, we'll need to come up with a way by which they can reproduce, or for that matter, have lunch without it being foul murder.