AIKA is a recently released Free-To-Play MMO. You can find it here for the United States and here for other nations around the world. You should be careful to get your client from the correct place, or it will not work – I learned the hard way. The Global site isn’t very forthcoming with the information about the countries it supports. It’s there, but not obvious.
My experience in AIKA is mixed. [I have no idea how to pronounce this. I guess it does not translate easily from the Korean.] There is a Wiki for AIKA, which has much useful information, but is not nearly as complete as the one for Guild Wars.