Stellaris is a 4X grand strategy video game developed by Paradox Development Studio and published by Paradox Interactive. Stellaris’ gameplay revolves around space exploration, managing an empire, diplomacy, and space warfare with other space-faring civilizations. It was released worldwide for Windows, macOS, and Linux on May 9, 2016, on February 26, 2019 for PlayStation 4 and Xbox One and on March 25, 2021 for Xbox Series X and Series S.

Stellaris is a real-time grand strategy game set in space, in the distant future. Players take control of a species, government, and ethics in its early stages of interstellar space exploration, right after the invention of faster-than-light (FTL) spaceship technology, ready to claim a place as one of “the species of the stars”. Depending on several factors, such as the ethics of the civilization and the player’s desires, the ultimate goal of the empire can range from galactic conquest, hoarding of resources and technological supremacy, to peaceful coexistence with or absolute destruction of all other sapient life. The player controls ships, including science, construction and military vessels. Combat includes space combat and ground combat and is more centered towards the bigger picture, preparation, and strategy. There are also diplomatic options such as alliances and trade agreements with other races.

The game begins either by picking one of the premade empires or using a player-made customized empire/species. The process of creating involves several different choices. The first of these choices involves picking a mixture of positive and negative characteristics (“Traits”) that make up their species. Next, the player customizes the empire of their species. In this phase the player chooses the ethics and civics of their empire (with Ethics and Civics points, respectively) which are meant to represent the ideology the empire has adopted and they can give various buffs, restrict certain features (a Spiritualist empire cannot use robots and dismantles them upon acquiring a planet that contains them, a Materialistic empire cannot outlaw robots) and governments from being picked (an Authoritarian empire is unable to be a democratic government and vice versa), and change the way information is presented to the player. Players also choose an origin, a kind of backstory for their empire. Origins can include originating from a world ravaged by nuclear warfare or starting with a secondary playable race, such as robots or a strong but unintelligent worker race. These secondary species are created in a similar process as previously mentioned.

All ethics, other than the later added Gestalt Consciousness, have normal and fanatic versions which represent the alignment of the empire. Fanatic versions of ethics give greater bonuses than their normal variants, but usually have even higher restrictions and always take up 2 ethics points instead of the normal 1 point per ethic. The ethic named Gestalt Consciousness makes the empire a hive mind or robotic empire, takes up all ethics points and gives new civics only available to hive mind and robotic empires. Megacorporations, a government type added in the Megacorp DLC, aren’t restricted ethics-wise like a hive mind is, but they can only choose civics unique to them. Both ethics (other than Gestalt Consciousness) and most civics can be changed throughout the game. Then, the player customizes the flag, name, homeworld, appearance of cities and space constructs, and ruler of their empire.

In most cases, the player begins with a single habitable planet in their territory, several mining and/or research stations, a construction ship, a science ship, three small warships, and a starbase. Early gameplay consists of exploring and colonizing space, while mid-game activities include either warfare or diplomacy, depending on the chosen play-style, but can also be filled with a vast amount of micro-management. The economy of a player’s empire throughout the game is primarily based on 5 main resources: energy credits, minerals, food, consumer goods, and alloys, each having a primary purpose to contribute to the player’s economy. Advancement in Stellaris is achieved through technologies and traditions which progressively scale in cost for the player to achieve, but provide better features for the player as the game continues. In the late game, crisis events can occur that have galaxy-wide implications—for example, an awakening of dormant sentient AI or an invasion by extra-dimensional or extra-galactic forces, the former two always being triggered by careless empires. Paradox hoped that this would address a common late-game problem in 4X style games; whereby one faction is so powerful that their eventual victory is inevitable, resulting in frustrating gameplay.