Though we would all love to have a fully developped Core, we do not plan to add any more domains at this time. It's not a hard "no it will never happen", but adding domains takes a lot of work and dedication. It would have to offer unique features in sufficient quantities to make it really interestings. It's a massive time sink investment few of us dev can afford at this time. Fewer have the skills to realize it. I don,t. When I signed on, I had high hopes of making Lekar, Falkovnia. The result was mediocre at best
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It is more likely that we'd expand on existing domains, or maybe have parts of certain domains as "oubliettes" in the Mists, rather than add a full fledge domain.