Thanks - I gave it a try, but I wouldn't recommend it.
I was selected, and they wanted me to produce an outline for my pitch which I did following their guidelines (which are vague and sometimes conflict with themselves). They asked for dozens of rounds of revisions providing just a little more information on what they wanted each time. You can try to base your work on examples from their previous games, but these don't seem to match what they are actually asking writers for now, so you're pretty much shooting blind.
All in all, I took all the suggestions (even though they sometimes conflicted with earlier suggestions), but they ultimately decided they didn't want to continue after they criticized two different aspects of the outline and I politely pointed out that those aspects had been on their suggestion. They suggested I post it to their Hosted Games, which do not pay an advance, so I wonder if it might be trick to get people to write without the advance or support.
I started out enthusiastic, but they really zapped the fun from writing.
It's frustrating to keep rewriting to adjust to information they could have provided right off the bat.
I probably invested over 20 hours in this for zero reward.
Beware!