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I see your point about the city, and even the fighter bay.
The ship was a 1 week project.
I made the city in 40 minutes.
All in all, I think adding ramps and making a jagged and "realistic" transition to the lava from the city would up the brick count significantly.
Right now most people can play on it with minimum brick lag, I often forget how many people have crappy graphics cards until I finish a really great, detailed build.