I've had this idea for a while, pondering whether to post it or not. But when I saw Meshon's Moon Gems of Valsa, it was like a go-ahead... so. Just don't ask me about the difference in date between now and then
In short:
You map it.
You write it.
With every WIP picture, some more story. And so on and on.
I'm sure we won't expect anyone to write a full novel but a short, well-fleshed out story - and the map to accompany it. Now I can say at once that most, if not all of us here are fantasy readers. Another group of us are writers.
I do think that a month would be a bit harsh for such a challenge, but, come on, we don't want the next bestsellers .
I'm still not sure if this would be a reasonable challenge, so no worries if I'm thinking over the star system...
And of course it needs tweaking.