if you like scripting i know the perfect games for you but they are fps games and not mmo. either starsiege tribes wich is pretty old now or tribes 2 wich is old but not that bad graphics. they both have insane costumization as in scripting, skinning, modeling. both are free too. search on fileplanet for either and if you choose tribes 2 read this forum on how to connect
http://www.tribalwar.com/forums/showthread.php?t=500559.
