It seemed like the silliest crossover in history, didn’t it? Square Enix’s Final Fantasy series, full of emotional and (relatively) mature protagonists clashing with Disney’s historically kid-friendly characters didn’t make a lick of sense at first – honestly, we feared that both companies involved had lost their minds. But once Kingdom Hearts released in 2002, this concept proved to be remarkably fruitful for fans of both parties. The pairing turned out to be absolutely wonderful and – dare we say – magical.

But it had its issues. The combat was a little bit sloppy, the story wasn’t up to Square’s high standards, and the means of traveling between the different Disney worlds, called the “Gummi Ship,” was a flawed game mechanic that took away more than it added. These problems and more were completely solved when Kingdom Hearts II came out, just four years later, fixing all of the our gripes while expanding Kingdom Hearts from an adorable mash-up into its own, remarkable series, earning it a spot on our list of the 100 best games ever.

Kingdom Hearts II’s greatness comes through not just its witty inclusion of Disney characters or its perfect selection of Final Fantasy tropes (though they certainly helped), but in its boldness. Square and Disney could’ve just said “yeah, so, more cartoons,” but that didn’t happen. Instead, they expanded on the story of the original, pulling in new Disney and Final Fantasy characters, and adding some of their own, too.

One of the most controversial, and important, introductions was the misunderstood Roxas. Square, who had spent the entirety of the first game allowing gamers to fall in love with protagonist Sora, outright replaced him for the game’s first act, sending some into an indignant rage. But there was a purpose to swapping out the hero for a blonde newcomer – he was part of the longer play to evolve Kingdom Hearts, a theme that permeated the entire story.

It wasn’t merely a small, fun journey through Disney settings – it was a massive, epic story that was complex enough to spawn five handheld spin-offs without breaking a sweat. Though it was hard to wrap our heads around at first, the introduction to the new enemies and organizations of Kingdom Hearts are part of what made Kingdom Hearts II so good, and helped it become more than the sum of its (already significant) parts.