Don't get me wrong, it is a lovely game: the music, the graphics, the controls (for the most part)- I feel like this is a nice little zen game, as far as gameplay and design are concerned. You can't ever die, there's not even fall damage and no battles at all. The puzzles are non-stressful and the only reason I got frustrated a few times was because of mistimed jumps (my bad).
But that story is absolutely horrifying! Can you imagine what it would be like if you knew that you and your entire world were nothing but someone else's dream? And when they wake up, your entire world will vanish as if it never existed. Even worse, your entire quest is meant to bring about that moment when you vanquish the final nightmare, and in a brilliant flash of light, everything vanishes. Your entire quest, your entire reason for existing, was to destroy your world, make it all disappear, never to return, never to be remembered.
That's this game. Grim and terrifying.