GMOs, or Graphic Model Overrides, are physical 'shells' or 'skins' for your navi that can change their looks. Or in simpler terms: ALTERNATE COSTUMES!
A GMO can be practically anything you want. You could make an ice-user burst into flames for one GMO, or turn into some sort of metal monstrosity for another. Or a woman. Or a man! Or some sort of alien. You can even RP your attacks differently for each GMO, and use a different weapon for your buster! (Though its' stats remain the same.) They do not take an action to activate during battle.
GMOs are obtained through leveling: You get a free .GMO every 5 levels, starting with one at level 0.
or by requesting a mission from one of three sources:
-The Mission BBS
-A GMO cannot make your navi into anything too huge. (A house, for instance.)
-A GMO can't make you too small. (like an ant.)
-No Copyrighted characters, just like normal registration.
-No making copies of other people's characters (from THIS site).
-While GMOs can make you into, say, a slime monster, or a puddle of sentient water, it's worth noting that these are purely cosmetic changes. You may get some interesting RP situations or reactions as a result, but mechanically your character's chances of being hit (Or hitting) remain the same.
GMOs are registered here.