Final Fantasy 6. The Floating Continent is a narrative climax: you've explored the entire world, the Emperor is there, Kefka is there, you believe they have nigh ultimate power, and you need to stop them NOW. Then you face a pseudo-boss gauntlet to even GET to the island, Atma shows up with then-unique boss music, you can't leave in a traditional manner, and even the way the savepoint before Atma is 'hidden' feels final dungeon-ish.