Some ascension perks are now part of the base game, and new ones were added in later expansions, along with new megastructures, but Utopia still adds lots of exclusive stuff, including the ability to indoctrinate primitive species, specialise slaves and build habitat stations. Hive minds, meanwhile, introduce a new way of playing the game with a host of unique mechanics and a special government type, letting you create a utopian collective or consume the galaxy. With ascension perks you get game-changing bonuses, new mechanics and a whole host of other substantial rewards for completing tradition trees, turning your species into master terraformers, transcended psychics and a whole lot more. With megastructures you get fun new toys to play with and big projects to embark upon, like ring worlds and Dyson Spheres, giving you more room to build and more ways to generate resources. While a lot of DLC goes specific, Utopia's broad improvements benefit pretty much everyone.
Paradox knocked it out of the park with Stellaris's first expansion, Utopia, and now the additions of megastructures, special civics like fanatic purifier, hive minds and ascension perks feel very much like foundational features. Release date: April 2017 | Store link (opens in new tab)
