There's nothing wrong with your idea per se, but what makes the kingdom worth saving? If the kingdom isn't interesting in some way, would your audience really care whether or not that it is saved?
It's the little things in life that surprise us and make us in awe. The tiny touches in life, that are so detailed and intricate - they can't even really be called 'Ideas' that will make or break your story.
I always love an old fashioned 'save the world' story. You just have to put your own 'pure essence' into it. We want to learn what you are about, not what final fantasy developers are about.
So therefore, how is your world interesting and different from all the other worlds? What is the tone, the artistic style? Subjectivity is very important here. What are some inside jokes that you heard that you could explain them to us, the audience? What do you see in your own mind's eye?
I just played a game that actually used Final Fantasy 7 music. I wanted to seriously VOMIT when I heard that. (The game wasn't bad though, and if it wasn't for the final fantasy throw-up, I'd probably still keep playing it) I'd much rather them just use the RTP music that game with their game maker, but to use 'final fantasy 7 music' just makes me cringe in agony. As well as people who have elemental attacks but always have to name them 'Firaga' and the like. I mean come on. That is somebody else's vision. It's not YOURS. What do YOU think, where do YOU want to go, what are YOU about? How are you interesting and unique and special? How are you a firework, ala Katy Perry? When your colors burst, what are they?
All of these are important if you want to suck people in your world.
Zelda has already been done to death by the way. It's okay to have a Zelda-style game, but what is your spin on things? You are not Link, you are not Mario and you are not Cloud fucking Strife. You are you! And we want to know about YOU. Not those characters who were created for mass appeal and for everybody to like them.