[quote=@Rai]
For a GM this is a delight. You can create characters types and roles that need to be filled and simply let others work within a boundary to sell the character right and boom you've got a coherently directed story. But for the player you'd have to be down for seeing the story and characters the GM is making come to life without intruding beyond the subtle actions and turns the characters can make.

Maybe to bring a medium you could have the GM lay out roles that need to be filled and character archetypes and such. Have people apply with a brief summary of their idea of a character. You choose the one that you like the most as GM THEN you let them make a CS, and work with them on it also so you both are happy with it. As the story progresses as long as the players feel like they are making a change in how things progress then its fine to keep it rather narrow in progression. You want to get to point a to b and so forth with the in between being something everyone can agree on would be fun and work with the story. 
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It needs a balence, you need allow enough room to keep people allowing some creativity. 

Like maybe having to have certain classes or roles but beyond that rest is up to player on direction. 

Ie, knight, rough age and rank.