This is a premise for a storyline for a game that I am planning on starting sometime in the next six months. Any feedback would be greatly appreciated. Looking for any additional ideas or comments. Also, anyone got an idea what an appropriate length would be in pages for a story similar to this?

Helps to have included the story idea. =)

The protagonist loses his father the king of a kingdom in a world similar
to Middle Earth at a young age. With no other heir to be found and the
protagonist too young to take the throne, the kingdom is thrown into
civil war. He is cared for by a man close to the former king who treats him
as a slave. The only hope for the kingdom is a rumor that someday this child
will claim the throne his father vacated.

So far so good!

Is the PC the son, or someone else whose goal is to save the son?

Also, what is the motivation behind the Man Close To The Former King? How does he benefit by keeping the son as a slave? Why did he not kill the son straight away?

I was thinking the guy that is keeping the son a slave would be after the throne
himself. His keeping the son a slave could be a token to either groom him as a puppet king he can control.(at least till the son becomes aware of his plot)

I may also change the fact that the son is a slave.

I don't want to sound too depreciative, but... You have close to nothing, here.

I mean, since you don't know where you story is headed, and who your characters are going to be, then, there isn't much you can draw safely.

plus the fact that it sounds VERY classic to me. It is very much like Aragorn coming back to Gondor, and being held as a slave by Boromir, or something close, anyway. Is there anything you wish to include in your story?

Well I wouldn't say he has 'nothing' obviously he has enough of an idea to run with. And I think that there is a significant amount that he probably hasn't told us about this kingdom and the civil war. Like for instance the other Nobles or bandits attempting to claim the throne. Or the people who will bow down in allegiance to an heir to the throne.

And it doesn't sound like Tolkien at all it sounds more like "The Sword in the Stone" or at least to me.

And in some ancient cultures to be a slave was very pretigious in some cases. It's more like being a servant in todays terms depending on what type of slave you were. If you were slave to a common peasant then you probably wouldn't have much prestige and if you were a slave to a rich Noble then you would be treated better. Look up somethings about rome and slavery. There is a difference between America's form of slavery and other parts of the world during different time periods, just so your aware.

I tink the appropriate length of the story would depend on how long an RPG you wanted it to be. But still the back story can be as long as you think is necessary to explain the events prior to the start of the game. I would suggest a simple Timeline marking the major events of the era in the kingdom. ke the land and world as small as you can. Make the characters simple and then if you feel it necessary make things more complex in the future. Well thats my two sense take it for what its worth.

you are going to need to flesh is out a bit. first question on my mind was why is there a civil war? i'd like more details on this point.

Well, the "civil war" comes about due to the absence of a king and the fact that the only heir is no where to be found. Henceforth, various people are fighting each other for the throne.

Also, I am thinking I may drop the whole slave son idea and go with the main character as one of the people fighting for the throne.

Then let me tell you that you're heading in one deep wad of §#!T, because you'll have to describe ALL the factions and make them reasonable, but only ONE being likeable, unless your player suddendly wants to turn on your character and to fight for another faction. and there is onjly so many ways to be evil or simply bad.