I am with dreamless. I completed my first game of kingdom hearts with only kingdom key! I died a whole lot and i was like, man i keep dying! Then right at the final save point in the game i found out i could use keychains! I was wondering why that ultima weapon had so much rare ingredients! So for the final boss fights i used ultimia weapon. But for the rest of the game, the kingdom key. On my next game (expert) I was smart enough to upgrade keyblades as i got them otherwise i would die even more in expert!