try..

http://www.mapleglobal.com
http://www.runescape.com
and try..
http://www.nexon.net (this is where you can download maplestory, audition, and kartrider)
ooh i forgot this o.o
http://www.ijji.com (gunbound is really good =] but i prefer maplestory ><)

oh.. and a paying game you might like is ragnarok but you have to pay.. although you can play on private servers ._. illegally ><