A cool expansion idea from shasla5...
Started with a few select planets, you could make a few planets fly aroundable. Making use of the docking ring would ensure a smooth ride and no damage, but you can actually enter the planet form anywhere. The planets' surfaces would be composed mostly of the same terrain repeated itself for countless miles, but on some planets there would be other cities with places you could land. City buildings would be destructable. You could get in planetary dog fights with friends. Another idea: make the people in the universe smart. If you destroy a station, they will rebuild it, or repair it if you damage it.
The Monkeys are coming. Beware!
The Monkeys are coming. Beware!