In KH1 Sora, Donald, and Goofy are traveling to worlds to find Riku, Kairi, and Mickey. Riku's fall into darkness and Malificent's plots are roadblocks to the journey, and it gets more dangerous as it progresses. You want to stop Disney bad guys from doing bad things. And with the exception of Hades, Sora clears them out by one. Each experience cements his bond to Donald and Goofy, which turns the tables against Riku at Hollow Bastian for a nice climax.
I feel it remains the KH game with the best told story. One can scoff at light, darkness, and hearts ad nausem, but the journey was exciting.