Oxygen Not Included

1. Summary

Oxygen Not Included is a colony sim where the threats are gas, water and heat rather than enemies. Positive reviews praise that simulation and a loop where every fix creates the next problem and every collapsed colony teaches something for the next one. The cartoon art, the duplicants' animations and the sound win people over, and long-time players credit years of free updates for keeping them around. Some reviewers call it the best game they have ever played.

How the game teaches itself is the subject negative reviews raise most. 30% of them blame the steep learning curve or the lack of in-game explanation, and several say they needed YouTube or the wiki to get anywhere. Positive reviews bring up the learning curve too, usually as a warning or an item in a list of cons, followed by the point that the game gets fun once its systems make sense. Players who expected a simple colony builder describe a rough first few hours. Smaller recurring complaints are duplicants who trap or endanger themselves, late-game slowdown, and updates that break mods.

2. What keeps coming up

What players praise

The physics and engineering simulationHigh

Players love that gases settle by weight, heat spreads through materials, liquids change state, and nearly every resource can be recycled into something else. "The genius of Oxygen Not Included is that every problem you solve creates three new problems." Some reviewers say it taught them real thermodynamics or chemistry, and several who work as engineers say it appeals to them, though one adds that the fluid and heat physics are not quite right. Heat gets singled out as the threat that builds up later: "Heat is the silent killer of worlds." Another player described the arc as "eventually you realize it was about heat all along". Players also like that problems rarely have one answer, so they can use the buildings the game gives them or invent their own contraptions out of pipes, sensors and automation. A smaller group objects to the game's physics shortcuts, covered under the split topics below.

Addictive "one more cycle" pullHigh

Time disappearing is a running theme. Players describe sitting down for an hour and looking up at 3am, and long-time players say they keep coming back to it after breaks. Dozens of short reviews say nothing more than "addictive" or a variant of it. Reviewers also like that nothing forces the pace, so they can pause and think whenever a crisis builds: "There's no random enemies or events, and the game gives you as much time as you want to tackle new projects and deal with its difficulties."

Failure that teaches, and endless replayHigh

Losing colonies is part of the fun, according to dozens of positive reviews. Each collapse shows a mistake (a toilet next to the water supply, a heat source by the farms, an overloaded wire) and the next colony goes further. "Every time you fail or make mistakes you will begin to plan your next attempt immediately." Different asteroids, seeds and world traits keep restarts fresh, and difficulty settings let casual players make things kinder or veterans make them harsher. Several reviewers with hundreds of hours say they still have not reached space and do not mind.

Art, animation and duplicant personalityHigh

The Klei art style, the animations and the duplicants' reactions come up again and again. Players name their favourite dupes (Meep and Nisbet among them), laugh at stress vomiting and flatulent colonists, and praise the soundtrack and sound effects. Several say the cute look hides a hard game: "Bizarrely cute, scientifically creative, stressfully cozy." A handful of players dislike the art and its toilet humour.

Years of free updates and supportMedium

Long-time players praise the developer for updating the game for years after release with free quality-of-life changes, new content and animated shorts, and a few call it a labour of love.

Mods, guides and a helpful communityMedium

Steam Workshop support is a frequent plus, and players list mods they consider essential (blueprints, building ranges, bigger zoom, performance tweaks). Reviewers also credit YouTube creators and fan sites for getting them past the hard parts, naming Francis John, Echo Ridge Gaming and Magnet among others, and some call the community helpful.

Great value for the priceMedium

Players often point out how many hours they got for a low price and note frequent sales. "the value of this game 10 times exceeds its price" is typical of the tone. A few also say it runs well on old laptops, Linux and Macs in the early game.

Where players are split

The learning curveHigh

Positive reviews usually treat the difficulty as a hurdle worth clearing: they call the curve a cliff or a vertical line, warn others to expect several dead colonies, and say the game opens up once the systems make sense. For other players it is a wall. Some say the game feels like studying, and some fans of RimWorld or Factorio say it is far harder to get into than those games, with a few calling its complexity something that exists for its own sake. Reviewers also disagree on how to learn it. One camp tells newcomers to play blind for the first colonies because figuring things out is the fun, while another says to watch tutorials from the start. The specific complaint about missing tutorials and documentation is covered under frustrations below.

The DLCsMedium

Reviews that mention Spaced Out mostly praise it, calling it a must-have that expands the endgame and changes how the game plays, though one player feels "Spaced Out should be in the base game rather than a separate dlc." The smaller packs get a cooler reception. Some players enjoy the new frozen biomes and Bionic duplicants, while others call them thin: "The other dlcs right now are more mehh, buy if they change somethings add content or are on a discount." A few long-time players object when a pack changes the base game, such as the removal of the fish feeder's grooming effect. One wrote that "the substraction of grooming effect from the fish feeder in the base game should really be compensated with another equivalent effect".

Micromanagement: relaxing or a second jobMedium

Some players call the game relaxing or play it like a cozy game. Others find the constant mopping, priority juggling and babysitting exhausting, including one who still recommends it: "If I worked this hard at a job I'd retire in a year." Several negative reviews say the game uses tedium as difficulty, and some positive ones admit it can "rapidly become a full time job".

Game physics and exploitsMedium

Players who know real physics are split on the game's simplifications. Some enjoy breaking the rules for fun builds, while others are bothered by mass and energy appearing or vanishing, gases that do not mix, packet-like pipes and missing latent heat. Doors come in for specific complaints: "Mechanized Airlock? Not actually an airlock." Players note that the usual seal is a few grams of liquid on a tile, which some call an exploit, and one complains that powering a door takes a huge transformer. Others accept these shortcuts as the price of a playable simulation.

A long mid game and no clear goalLow

Some players love that the game is a sandbox with no end. Others hit a mid-game slog where plastic, steel and power take hours of setup, or say they never had a reason to keep going: one called it "like life" with "no ultimate goals". A few players mention a hidden story and secrets as reasons to keep exploring.

Updates that change the rulesLow

The same update stream players praise also unsettles some veterans. Reviewers mention nerfs, rebalanced resources and drywall changes that broke their designs, and one warned that "the game you play in a year might be different from the game you play today." Another reviewer, still recommending it, said "sometimes free updates do change game mechanics enough that they break designs that have worked fine in you base forever forcing you to redesign".

What frustrates players

Thin tutorial and in-game informationHigh

Negative reviews raise this more than any other problem, and it fills many of the negative reviews from players who stopped within their first few hours. They describe a dense interface, a tutorial that "dumps text at you", and having to discover basic needs (outhouses, wells, research) by failing. "There should be a tutorial that provides a hands-on experience for new players." Several argue that a released game should not need outside help: "It's the game's job to make itself understandable and accessible, not some random youtuber's." Experienced players add more specific gaps: the in-game database lacks numbers that matter, building information is inconsistent ("Why provide melting point (or other info) for some buildings, but not for others."), and mechanics like rooms, germs and power grids are poorly explained. Plenty of positive reviews make the same point in passing, often as advice to keep a wiki or a YouTube guide open.

Duplicant AI, pathing and prioritiesMedium

The dupes' habit of trapping themselves, walking through scalding water, building themselves into walls and peeing in the water supply is a running joke in positive reviews and a real grievance in negative ones. "It feels like I'm constantly fighting the AI to stop my own Duplicants from killing themselves." Frustrated players say dupes ignore high-priority jobs and stand idle, fail to rescue incapacitated colleagues, and wander into toxic areas because there is no way to mark zones as off limits. One put it as "its like having a bunch of toddlers run a nuclear facility".

Late-game performanceMedium

Slowdown in large colonies comes up in dozens of reviews, many of them from players who still recommend the game. Players report freezes during autosaves, frame drops even on top-end hardware, and in a few cases crashes on autosave. "It uses a single CPU core to run the entire game simulation, which means I get 30 FPS or lower after mid-game." Players work around it with in-game tricks to cut the simulation load or with community performance mods.

Updates that break modsLow

Long-time players who rely on quality-of-life mods say updates keep breaking them: "nearly every update break most of mods". They add that broken mods crash the game without saying which one is at fault, and that tracking down the culprit is slow because "to enable a mod you have to restart the game each time." Some report the game switching off their subscribed mods by itself.

Crashes, launch failures and lost savesLow

A smaller set of reviews describe the game failing to launch after an update ("Since Bionic, not been able to get to the menu to Load!"), hanging on the loading screen, a Mac launch error, and saves vanishing: "I lost all my save game in the last update". Others say they found no bugs at all.

Content locked behind data collectionLow

A few players object that some cosmetic content requires opting in to data collection: "Oxygen Not Included locks additional content behind online data collection opt-in." The same reviewer says the game keeps prompting players to opt in, and another found the setting switched on by default without being asked.

Steam Deck and controller playLow

Steam Deck players are split. Some say it runs perfectly, while others report small text and awkward controls: "Terrible controls for Steam Deck - doesn't deserve its Verified status."

Missing features players keep asking forLow

A steady trickle of reviews ask for the same additions: co-op or multiplayer ("Wish it had co-op."), a built-in blueprint or copy-paste planning tool ("What we need is a copy/paste blueprint function, like Factorio offers."), moving buildings instead of rebuilding them, better UI scaling, and more languages ("Please add official Spanish localization").

3. The player conversation

Most of the conversation is warm and full of in-jokes. Reviewers laugh about dupes peeing in the water supply, about needing an engineering degree, and about the title being a lie because some oxygen is included at the start. Veterans with thousands of hours write short, affectionate reviews ("Time played speaks for itself").

Two groups of negative reviewers stand out, and their complaints differ. Newcomers who quit within a few hours write about the tutorial, the overwhelming interface and the feeling of studying instead of playing. Long-time players who turn negative write about mods breaking after updates, physics inconsistencies, late-game lag and changes to mechanics they relied on. Dupe behaviour annoys both groups.

In the week of November 18, 2024, the positive share dropped to 80% across 191 reviews. Reviewers date a free weekend to November 21 to 25 that year, and 19 of the 40 negative reviews written in those five days blamed the learning curve or the lack of a tutorial. Most of those 40 were written within a few hours of play, and many describe a screen full of buttons and menus, a tutorial that explains too little, and a game too complicated to be fun.

The week of June 22, 2026 dipped to 87%. Its negative reviews were spread across different complaints: a game that is too complicated or badly explained, tedium and micromanagement, gases that behave oddly, dupes that ignore outhouses or wander where they like, the data-collection opt-in, and one long-time player's objection that base-game Pacu were changed alongside the Aquatic Planet Pack. From July to October 2026 the weekly positive share ranged from 88% to 100%.

4. What the developers could do

1. Build a hands-on tutorial for the first cycles. Onboarding is the problem negative reviews raise most, and free-weekend players described a tutorial that hands them text instead of guiding them, leaving them to work out wells, outhouses and research by failing.
2. Fill the gaps in the in-game database. Players want consistent stats such as melting points, clear explanations of rooms, germs and power, and enough information that the wiki is optional.
3. Make duplicants safer and easier to direct. Reviewers ask for no-go or suit-required zones, smarter pathing that avoids hazards and dead ends, and rescue behaviour for downed dupes. Dupes trapping themselves comes up in positive and negative reviews alike.
4. Improve late-game performance. Players who still recommend the game flag single-core slowdown, autosave freezes and frame drops in big colonies, and some rely on community performance mods to keep playing.
5. Protect mod setups across updates. Long-time players want updates that break fewer mods, a crash report that names the faulty mod, and mod toggling without a restart.
6. Fix launch failures and save loss. A smaller set of reviewers report the game hanging on load after updates, a Mac launch error and saves disappearing from local and cloud storage.
7. Stop gating cosmetics behind data collection. A few players say the opt-in requirement for extra content soured them on the game.
8. Add the planning tools players keep requesting. Reviewers ask for copy-paste blueprints, moving buildings, real airlocks, better UI scaling and Steam Deck controls, in positive and negative reviews alike.