The community basically runs like this: At the beginning of each month, members submit a prompt for an FMA fic they would like to see written. A few days later, all participants are assigned a prompt; they have two months to finish their story.
The trick is, you can't swap prompts, nor can you tell anyone else (save for a beta reader) what your prompt is - the community is designed to let you test out new characters or situations that you otherwise wouldn't.
More information can be found here.
I hope to see some of you in this round!