I think this will be one of the best open worlds ever. With over 18,000,000,000,000,000,000(18 Quintilian!) planets, each huge and ready to be explored, you can name new planets and species, learn alien languages from stone obelisks, and do anything you can do to survive. Survival and exploration are very big themes in this, but it still has combat. Environment is very important, as the temperature is active and if you get to cold or hot without cover then you will die.