Thanks Kai.
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Well, SSharp, I'd say the Ottyo would fall into categories 2, 3, and 4, with number 5 being up to the GM's running the plots. Going by number 2, The grunts would be clever in a manner that would make a hunter say something along the lines of "Clever Girl." before getting mauled. The commanders are more of the cold and logical type, exploiting PCs' character flaws and personal values such as valuing life.
For number three, they are monstrous through their actions, though their appearance in battle is unnerving as well. Most of their actions have a point, and yes, if they kill children, that would have a cold and logical reason to justify it. They do things with a German efficiency despite their erratic and unpredictable nature in battle. For an example, if they want to interrogate someone, they're not even going to bother physically harming you themselves. They'll either do it to a friend of yours, bring in a Mishhu they raised themselves, or bring in a Mishhu they raised themselves to be 'used' on your friend.
Number four, yes, I intended them to be incredibly tough, speedy and nimble, capable of taking a beating and dancing a ballet. Think of a 'Big Sister' from Bioshock 2 and ratchet it up a bit. However, to balance this out, I'd give them weapons that are of moderate to low power in comparison to what Players may use or make what powerful weapons they have very large, unwieldy and showy.
Number five is debatable, and up to GM's for a reason. Besides their Organic Power Armored troops, I intended them to deploy what essentially amounts to fire vomiting attack dogs and small swarms of fluttering scout birds. The point of this was to give out the feel that the Ottyo were hunters who were setting the hounds on the players. This would outnumber the players, and in such a case they'd be up against less actual Ottyo but a numerically superior force. But, if a GM wishes it, a more conventional battle can be had.
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Ira, the Ottyo are not human at all. It's more of what Kai said. They're very alien in appearance, but have behaviors or traits that we attribute to ourselves, making them even more unnerving and alien. That's what I meant by being human-ish. A good example would be their laughter. Go onto youtube and listen to some hyenas at it, and that will give you a good idea.
As for alien biology, I decided to stay with carbon based lifeforms, however, have their blood be cobalt based in comparison to our iron based blood. This means that unless they have special organ/bone marrow grafts or other, they can't eat our food and we can't eat theirs. It will also rule out much of the medical equipment available on SARP as well.
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I second what Kai said! Actually read the thing please! Go ahead and ask questions, give comments/criticism. I'm usually on the IRC, so that's on the table too.