Frankly, the game mechanics and scales for "ring" and "sphere" worlds more closely match with what would be considered "L5"-type colonies in real life. Not that that's a bad thing, but calling them "ring" and "sphere" worlds is somewhat misleading. It is totally unrealistic (as if ring and sphere worlds
are realistic
) to have a Niven-style ringworld or a Dyson sphere constructable in anything like an SEIV game's timescale. You'd need "Space Odyssey" timeframes for that...