How to Play Oxygen Not Included (The Ultimate Beginner's Survival Guide)

Welcome to the inside of a space rock. You are in charge of a group of genetically engineered clones called Duplicants (or "Dupes"). They are very cute, very eager to help, and completely devoid of common sense. If you do not micromanage their every move, they will hold their breath until they pass out or pee in their only supply of clean drinking water.

Quick Answer

To survive the early game in Oxygen Not Included, you must secure basic needs before your resources run out. Immediately build an Outhouse and Washbasin for sanitation, a Pitcher Pump for water, Cots for sleep, and an Oxygen Diffuser for breathable air.

Phase 1: Rolling the Perfect Starting Dupes

Before you dig a single block of dirt, you have to choose your starting three Dupes. Do not just hit the "Start" button. You can click the "Shuffle" button as many times as you want to get the perfect team.

For your first three Dupes, you need this exact setup:

• The Digger: Look for a Dupe with a high "Excavation" skill. They will dig through rock faster, which is how you expand your base and find resources.
• The Nerd: Look for a Dupe with a high "Research" skill. They will spend the first 50 cycles staring at a computer screen to unlock new technology so your base doesn't collapse.
• The Go-Getter: Look for a Dupe with high "Athletics" and "Operating." This Dupe is your designated battery charger. They will run on a giant hamster wheel to power your base and carry heavy rocks from point A to point B.

Traits to Avoid at All Costs:

Never pick a Dupe with the Flatulent trait. They will randomly fart Natural Gas, which is unbreathable, messes up your gas management, and eventually ruins your base. Also, avoid Narcoleptic (they fall asleep in dangerous toxic slime pits) and Bottomless Stomach (they eat twice as much food as everyone else).

Phase 2: Cycles 1 to 5 (The Bathroom Emergency)

When the game starts, hit pause. You have a small bubble of breathable air, but the clock is ticking. You need to solve sanitation, water, and sleep immediately.

1. Do Not Pee in the Water

If a Dupe has nowhere to go to the bathroom, they will make a "mess" on the floor. Gravity will pull that mess straight down into your clean water supply, infecting it with food poisoning.

• Dig out a small room.
• Build an Outhouse.
• Build a Washbasin right next to the door.
• Crucial Step: Click on the Washbasin and click the arrow button so it points towards the exit. This forces your Dupes to wash their hands after they go to the bathroom, not before.

2. Secure Clean Water

Find the closest pool of clean, blue water. Build a Pitcher Pump hovering over it. This allows your Dupes to manually bottle up water to wash their hands and do science experiments.

3. Make a Bedroom

Sleeping on the hard floor causes massive stress. Dig another room and place three Cots inside. If you surround this room with doors, the game recognizes it as a "Barracks," which gives your Dupes a morale bonus for sleeping in a real room.

4. Create Oxygen

Your starting air is running out.

• Build a Manual Generator (the hamster wheel).
• Build a Tiny Battery.
• Build an Oxygen Diffuser.
• Connect them together with Wire.

The Diffuser turns Algae into pure Oxygen. As long as your athletic Dupe runs on the wheel, your base breathes.

Phase 3: Cycles 5 to 15 (Science and Starvation)

Now your Dupes are breathing, but they are getting hungry. The starting food rations will run out fast.

The Golden Rule of Food: No Mush Bars

The game tricks beginners by giving you a machine called the Microbe Musher. It turns dirt and water into "Mush Bars." Do not make Mush Bars. They waste tons of your precious water, require constant power, take forever to make, and give your Dupes terrible diarrhea.

Plant Mealwood

While digging, you will find Mealwood Seeds.

• Build a row of Planter Boxes or Farm Tiles.
• Plant the Mealwood Seeds.
• Mealwood only requires Dirt to grow (which you have thousands of tons of). It grows fast, and Dupes can eat it totally raw without you needing to cook it. Plant about 5 Mealwood plants per Dupe to completely solve your early-game hunger.

Start Researching

Build a Research Station and a Super Computer. Assign your Nerd Dupe to start unlocking the tech tree. Prioritize unlocking Advanced Power (for Coal Generators), Farming Tech, and Plumbing.

Phase 4: Base Layout and The Physics of Gases

As you expand, you will realize this game is actually a physics simulator. Gases have different weights, and they will naturally separate in your base over time.

• Hydrogen is the lightest gas. It floats to the absolute ceiling. (Later, you can pump this into generators for clean power—see our guide on what to do with Hydrogen).
• Oxygen is average weight. It stays in the middle where your Dupes live and work.
• Carbon Dioxide (CO2) is super heavy. Every time your Dupes breathe out, they make CO2, and it sinks straight to the floor.

Build a CO2 Basement

To stop your base from choking on red gas, dig a massive, empty hole at the absolute bottom of your base. Leave gaps in your floors or use Airflow Tiles so the CO2 can fall down into the pit. This keeps the main living areas full of green oxygen.

For advanced removal, check out our guide on how to get rid of Carbon Dioxide in ONI).

Phase 5: Cycles 20+ (Upgrading Your Life)

You survived the early game! Now you need to automate things so your Dupes don't spend all day running on wheels and emptying outhouses manually.

Upgrade Your Power Grid

Once you unlock it, build a Coal Generator. But here is the secret: you must hook it up to a Smart Battery using an Automation Wire. The Smart Battery tells the generator to turn off when it is completely full. If you don't do this, the generator will burn through all your coal for absolutely no reason.

Build Real Toilets

Outhouses run out of dirt and need to be emptied manually by your Dupes (which is gross and takes time). Research plumbing and build Lavatories and Sinks. Run clean water into them, and run the polluted water out.

Manage Dupe Stress

If your Dupes get too stressed out, they will have a meltdown. Some will start destroying machines, while others will aggressively binge-eat all your food. Keep stress low by cleaning up liquid spills with the Mop tool (nobody likes wet socks), building a Great Hall (a room with a Water Cooler, a plant, and Mess Tables) for them to eat in, and giving them enough downtime in the schedule tab.

Summary

To truly master Oxygen Not Included, you have to change how you look at the game. There is no trash. Every single problem is just a resource you haven't found a use for yet.

• Too much scalding hot water? That's free energy for a Steam Turbine.
• A room full of toxic Chlorine gas? That's a free sterilization room to kill germs.
• Polluted Dirt everywhere? Compost it to grow more food.

Take it slow, pause the game often, and remember: if everything catches on fire and your base collapses, you can always just start a new colony. Good luck down there!