you need to post more details because otherwise it´s very hard to say if it is a good concept or not. From what you´ve written it could be almost any game from thousands out there. It´s the details that divide the good games from the bad ones.
Also, I recommend you not to rely on others people help. What you won´t do yourself, won´t be done
As @ViliamFiedler says, you’ll struggle to get anyone to help you with a vague idea like that. You’ve got to sell your idea, tell people WHY they should spend THEIR time coding it for YOU. What’s the story about? What mechanics does the game utilize? Who are the characters, and how many of them are there? Does it use stats? How long is it? Do you plan to publish it through CoG or keep it dropbox(etc) hosted? And all the rest.
You are 17 years old in a world very diffrent to ours. It is in the medieval age but at the same time also in the future.
In a dream you speak with someone and he tells you that you are the chosen one, you must find three tomes in the world of “century” but the problem is nobody knows were they are. You must go on a journey with three others you will find on the way. But you must be fast because there are people called “The Ravens” who want to have the tomes too so they can free the demons.
The game has: gender
No race: you are human but in the game are mythical creatures and other races.
Classes: these will affect the storyline but only from chapter 2
@MaraJade While Ender’s Game is amazin’, and the most well-known series he wrote IS the Ender Saga, he writes a lot of cool stuff (although Wyrms is rather twisted). Everyone should read his stuff, an’ Garth Nix’s stuff if they like fantasy, though Garth Nix did do Shade’s Children which is sci-fi.
Um, an’… Snow Crash! Everyone should read Snow Crash! Yup!
Now, I’d love to be shameless advertisement but it makes me feel bad.