I'd guess Aussies might be fairly powerful all-rounder, pretty much as Poland. They have good bonuses either inland or coastal. Coastal cities receive bonuses from their UA. Housing and extra yields are amazing (usually coasts get a bonus to appeal). Inland cities benefit from Outback Station. It seems powerful and versatile. Food and production from flat land? Count me in. Outback triangles in plains get 2f/3p, which is nothing to sneeze at. All in all, they look suited for a Science or Cultural Victory. High appeal tiles mix well with Resorts, while all the food and production lend themselves well to science. Fun fact about Citadel of Civilization: If you declare war and your new enemy is suzerain of a CS, the CS DoW's you, which counts for the Defensive Tactics inspiration (Be the target of a Declaration of War). If this also triggers Citadel of Civilization, we're looking at downright OP category here.