This is a Castle and its for CTF and the team outside the castle has to get into the castle and retrive the flag. Download Map http://www.bungie.net/Forums/posts.aspx?postID=17105938
I'd like to seen you expand on the design of your castle since all that are made these day are 1, on Foundry, and 2, are made of crates. This looks good though, but maybe just make your castle stand out from the others out there. Good job though.