My take:  it could be that the world is becoming more and more creatively sterile, and our 'kids' are fighting against the dying light, as they are themselves quite creative. Everything is just cookie cutter, mass-produced nonsense, imitations of imitations of imitations. This is because The Nine Greek Muses have been chained up in dungeons inside the public unconsciousness. Each Muse could be trapped in their own dungeon, themed around what that Muse represents.<br/><br/>By setting them free, they're literally returning creativity back to the world. This, of course, could segue into the Big Boss; whoever, or whatever, managed to imprison the Muses in the first place.  I don't know if this quite counts as being bigger than the other games, but I feel like the spiritual neutering of art and culture, a reduction of humanity to a bland and homogeneous paste, is at least on par.<br/><br/>This would also show why the musical motif is so important to the story. Thoughts?