Very different from the two main PS2 games, but crucial to understanding the full story.

It tooks some time to get used to the card-based battle system, and I don't think I'll ever quite master it, but it's easy enough to fudge your way around it and muddle through. I played the games in a very strange order - I started with Kingdom Hearts and didn't get very far, played and beat Kingdom Hearts II, went back and beat the original Kingdom Hearts, and am now in the middle of Kingdom Hearts: Chain of Memories. This game is definitely filling in a lot of blanks and clearing up a lot of confusion after I realized that the end of the first game didn't really tell me anything about The Organization. If you're a fan of the series, I definitely recommend playing this game to get the full story so far.