When I mentionned that my main character was born from a roleplaying game in my last post, a surprising number of you commented that it happened to them on a frequent basis. I used to have trouble accepting the strong influence of the games on some of my work, and the lesser but-no-less-important presence in the others. I came to the craft of writing through roleplaying, but today I can tell what works, and what doesn't.
This is what I transfer the most from my RPGs. I have created characters I love through the years, with a well-developped and often under-exploited background. It's a truth of gaming (especially online) that half the hooks you build into your backstory will never surface again. I love to explore those subplots. Sometimes they even become the main intrigue.
I find that character personalities translate well from RP to writing. Sometimes, however, changing their abilities and races might serve your story. There is a lot of 'epic' with RP, and I find not all of it fits with my style.
Perhaps this is only me, but the only plot I have kept from a RP was one that focused on a family's internal relationships. I find that most plot require heavy work to fit the narrative structure. Pluck elements and premises if you like them, but I don't recommend clinging to all scenes or to the way the story evolved.
EDIT: It just occured to me that a lot of the plots I've reused are Character Arcs. It makes sense, considering I mostly import characters.
While I have changed settings between a story from a RP and the novel form, I think this element can be transfered easily. You need to think about what you want (high or low magic, for example) and what serves the story best. DnD is a mash-up of many mythologies. Take the time to decide what you need, and take the time to check on the original myths, too.
By the way, this is not to say you should dump all orcs and trolls and elves and dwarves. When you write a novel, however, you need to think them through, explain them, and know what makes your setting unique.
I'm sure there is a lot more to be said, and this is a topic I'm likely to revisit. Roleplaying games are an incredible source of inspiration for me, but adapting them comes with a lot of problems. The potential is there, however, and a good writer knows how to tap it.