Oxygen Not Included is a survival simulation video game developed and published by Klei Entertainment. After being released on Steam's early access since February 2017, the game was officially released on July 30, 2019.

Oxygen Not Included is a simulation survival game. At the start of a new game, three colonists (referred to as duplicants) find themselves in an asteroid with isolated pockets of breathable atmosphere, with no memory of how they got there. The player is tasked with managing and taking care of these duplicants as they try to survive and create a sustainable makeshift space colony. The player must monitor the duplicants' hunger, waste, and oxygen levels to keep them alive. Each game's world is procedurally generated. The world is then subdivided into various regions or "biomes" that contain different and often biome specific materials and critters. While initial areas have a breathable atmosphere, subsequent areas are in a vacuum or lack oxygen, requiring proper preparation by the duplicants before they explore these areas. The world also contains several hazards such as diseases and extreme temperatures. The game simulates the diffusion of gases and equalization of atmospheres when a new natural chamber is opened, which can cause oxygen levels to drop in existing chambers, as well as the draining of liquids by gravity.

To help establish the colony, the player directs the duplicants to perform certain tasks, such as mining for resources, growing food, crafting equipment, researching new technologies, and maintaining their own health through nourishment, rest, and hygiene. The player does not control the duplicants directly, and instead provides prioritized instructions, from which the duplicants will then follow to the best of their abilities. For example, the player can order a conduit of wire to be built; which will have the duplicants collect the materials to make the wire, clear away any materials around the conduit's path, and then construct the wire. If the duplicants cannot access a source of copper for the wire, the task will remain uncompleted as the duplicants go to complete other tasks they can do. Duplicants have stats that determine how effective they are at certain tasks, and will prioritize tasks that they are best at. These duplicants' skills can be improved over time and practice.
What is Oxygen Not Included?
Oxygen Not Included is a space-colony simulation survival game produced and published by Klei Entertainment, the same studio that developed Don’t Starve. At the start of a new game, three colonists (referred to as duplicants) find themselves in an asteroid with isolated pockets of breathable atmosphere, with no memory of how they got there. The player is tasked with managing and taking care of these duplicants as they try to survive and create a sustainable makeshift space colony. The player must monitor the duplicants' hunger, waste, and oxygen levels to keep them alive. To help establish the colony, the player directs the duplicants to perform certain tasks, such as mining for resources, growing food, crafting equipment, researching new technologies, and maintaining their own health through nourishment, rest, and hygiene.