I just had what I think is a really good idea- tell me what you think. Since Metropolis was brought up, I was thinking about Coruscant itself.
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Picture this:
HAD ABADDON. Capital of the Republic. One side is nothing but a huge city, but the far side is a lava-filled, volcanic wasteland. It's where convicts, political enemies, and other criminals are sent. So you see, the entire story takes place on Had Abaddon (except for flashbacks).
Good idea?