Oxygen Not Included is a survival game released in 2019. It was created and released by Klei Entertainment. The game was first available on Steam's early access program starting in February 2017. It was officially launched on July 30, 2019.

Gameplay

Oxygen Not Included is a simulation survival game. At the start of a new game, three colonists (called duplicants) are on an asteroid with small areas of breathable air and no memory of how they arrived. The player must manage and care for these duplicants as they work to survive and build a temporary space colony. The player must watch the duplicants' hunger, waste, and oxygen levels to keep them alive. Each game's world is randomly created each time. The world is divided into different areas or "biomes" that have unique materials and creatures. Early areas have breathable air, but later areas are empty of oxygen or in a vacuum, requiring the duplicants to prepare before exploring them. The world also includes dangers such as diseases and very hot or cold temperatures. The game shows how gases spread and how air levels balance when a new area is opened, which can lower oxygen in existing areas and cause liquids to move due to gravity.

To help build the colony, the player tells the duplicants to do tasks like mining for resources, growing food, making tools, researching new ideas, and taking care of their health by eating, resting, and keeping clean. The player does not control the duplicants directly. Instead, the player gives them instructions in order of importance, and the duplicants try their best to follow them. For example, the player might ask for a wire conduit to be built, which would make the duplicants gather materials, clear space for the conduit, and then build it. If the duplicants cannot find copper for the wire, the task will not be completed, and they will focus on other tasks they can do. Duplicants have skills that affect how well they do certain tasks, and they will choose tasks they are best at. These skills can improve over time with practice.

Development and release

Oxygen Not Included is created by Klei Entertainment, an independent game studio based in Vancouver, Canada. The game was first introduced for Windows during the PC Gaming Show at the Electronic Entertainment Expo in 2016. It was also announced that the game would later be available for macOS and Linux. A version of the game that was still being developed was released to players through early access on February 15, 2017. Initially, the game was expected to leave early access on May 28, 2019, but the release was delayed until July 2019. Klei Entertainment also shared plans to create downloadable content (DLC) for the game. Some DLC was later added, including the free Automation Innovation update, which improved the game’s automation system and added new tools like ribbon cables, and the paid Spaced Out update, which introduced a radiation system, uranium processing, and bee farming features. Klei later stated that no more DLCs would be released for Oxygen Not Included, instead offering free updates. However, three additional DLC packs were later released: The Frosty Planet Pack on July 19, 2024; The Bionic Booster Pack on December 13, 2024; and The Prehistoric Planet Pack on June 12, 2025. Klei’s Johann Seidenz mentioned that games such as Dwarf Fortress, Prison Architect, and The Sims inspired the design of Oxygen Not Included.

Reception

Metacritic, a website that collects reviews, found that Oxygen Not Included received mostly positive feedback from critics.

Nate Crowley, who wrote for Rock Paper Shotgun, praised the game's design and how players progress, but wondered if the increasing complexity might discourage casual players, especially those without science or engineering backgrounds. GameCentral also gave the game an 8 out of 10, praising the game's scientific accuracy and design, but noted that the difficulty level could be a challenge, especially since there are few tools to help players learn within the game.

Oxygen Not Included was nominated for "Strategy/Simulation Game of the Year" at the 23rd Annual D.I.C.E. Awards and for "Strategy/Simulation" at the 2020 Webby Awards.