I like the idea of race-based guilds. I myself run an Elven-only guild. I feel it adds to the roleplaying aspect of the game as races do tend to culimate together in one place. Not every race is prone to all-out acceptance of the other races. It\'s not racist, it\'s natural.
One of the problems you will encounter, though, is getting people to join. Getting people to join any guild is a tough matter, but limiting possible candidates to a certain race cuts the number of applicants drastically. But with future releases and with more people in PS it will be sure to catch on. Just remember, and this is true with any new guild, it could take weeks to get even one member. And months before you have a substantial amount. The key is to be patient and not to give up.
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For some pointers on creating a race based guild you could check the Calen Vakhar\'s site out.
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I think an all-dwarf guild is a good idea.