Ja, but its for the psp. Well, theres a Chrono on FTT, so I thought that was you. My mistake.
Anyway, if you plan to play Kingdom Hearts, you MUST play them all.
Storyline wise, Kingdom Hearts goes like this(so far):
Kingdom Hearts: Birth By Sleep(PSP)
Kingdom Hearts(PS2)
Kingdom Hearts: Chain of Memories(PS2/GBA)
Kingdom Hearts: 358/2 Days(DS)
Kingdom Hearts II(PS2)
Kingdom Hearts: Coded(iPhone, in 2011)
And if you don't play just one of them, I garentee ALOT of stuff won't make sense later on. :P