They are four species you can be and if you are a reploid you can become any other species with the right Magic. I will explain each one of them.
Reploids: Reploids are robots with Human traits such as thinking and feeling. They have emotions and the whole gig but they are much stronger than humans and cannot reproduce.
Humans: With out Humans the Reploids could never exist Humans are much weaker than reploids but they have feelings and needs to and they can reproduce so if they are killed there offspring will quickly avenge thier parents. Humans onfourtunally can't use Data chips but are way better at Magic and are smaller than reploids so they can be more stealh especially with the right stuff.
Monsters: Monsters come in all shapes and sizes its all in your imagination to what they can do even though most monsters I have seen tend to be evil and really dumb. Monsters cannot use Data chips just like Humans but they are just as strong as any reploid.
Aliens: From another world think of Aliens as one of the best but thoughset classes to play since they can use data chips, can be strong as a monster or weak as a human, and are much smarter than any human or reploid.
All right, around here you are limited to certain classes each Class has more or less abilities than the others. If you want to become another class you have to earn Job points. If you want to get more magic and better limit breaks you will have to get Ability Points. I am setting up this place like Final Fantasy Tatics and FF7 with a reploid edge to it( some of these classes I made myself ).
Squire: Your basic Reploid he can do a little of everything but is not really good or bad at it this is who you start out as. They can only hold 2 special weapons at a time, and 1 normal( not including sword and X buster). To boot they can only do a Level1 limit break. Even with the weak Limits The Squire can use items to attack and Cure always bring own of these guys for basic curing needs.
Kinght: Cooler than the Squires, Knights can use Level 2 Limit breaks to cause mass destruction to those big bad guys, Unfourtunally they are slower than the squire and take a long time to use magic with the help of Materia. The Knights can carry 4 special weapons and 2 normal Weapons ( not including a Long sword and X buster. )
Monk: He is a Martial Arts expert wich can break your neck in a minute. Monks can Use Level2 Limit breaks and Learn more Martial Arts Techniques if they want makeing them pretty strong. There only disadvantage is a low defense which can be made up for by there speed and power. Monks really do not need weapons but they can carry 3( including X buster. you may not know but to them that can be a little wieght.) if they wish.
Geomancer:Bad guy look out! This guy fights with nature and as the same physical ability of a Monk and the Weakness of the Knight. Though they don't last long they don't need magic because where they stand a new spell is cast.
Ninja: Master of the darkest form of Martial Arts The Ninja can go through a whole Mission Killing and not even be noticied at all. Ninjas can also have a higher speed, and defense then the Monk but not by much. Ninjas can also carry 4 special wepons and 2 normal weapons. ( not including the basic shuriken and X buster.)
Wizard: Weaker than the Knights The Wizards rely only on there ability to use the mystic arts.THey can start out with 6 spells, 3 curing and 3 to attack. They can also learn Magic quicker than any body else. Instead of using the attack limit breaks they will use curing Limits and stunning Limits.
Mage: Know this guy packs a punch! From here you learn the more powerful spells much faster like lit3 or Meteor the most powerful spell of all. All this means is that you have just become a better Wizard.
Thief: Hey if you don't have a thief what do you have? these little weasals master the art of Mug so they can take your saber and hurt you to. They use a Level 2 Limit to blast there target if they get caught. There physical weakness is there advantage and yet disadvantage to since if you don't Kill them they Kill you.
Warrior Mage: One of the Best classes They can both use items and Magic. They can also take advantage of the powerful level 3 Limit Break only dwarfed by The Holy Knight's Level Four Limit.
Holy Knight: The Ultimate warrior they can do every thing under the powers of Light. they're only disadvantage is that they are the hardest to get.
Black Knight: The Holy Knights only equal is the Black Knight which use Dark Saber to gradually suck the life of thier foe.