Oxygen Not Included is Klei Entertainment's colony survival sim where you manage a group of Duplicants trapped inside a procedurally generated asteroid. Every breath of oxygen, calorie of food, and degree of temperature must be meticulously managed through complex piping, ventilation, and power systems. The Spaced Out! DLC adds multi-asteroid colonies and interplanetary rocket logistics. With hundreds of hours of depth in thermodynamics, gas physics, and liquid mechanics, ONI rewards systems-thinking players who enjoy solving cascading engineering puzzles.
Starting Oxygen Not Included can feel overwhelming. This guide tells you exactly what to focus on during your first hours so you don't waste time on things that don't matter yet.
What Kind of Game Is This?
Oxygen Not Included is a simulation game built around gas management and pipe systems. The core loop involves mastering these systems to progress through increasingly challenging content.
What to expect: Time investment in learning mechanics, experimentation, and gradual mastery. The game rewards patience and knowledge.
Choosing Your First Build
| Build | Beginner Rating | Why |
|---|---|---|
| Researcher | Good (but demanding) | Parks at research stations full-time, occasionally operating telescopes for space data. |
| Farmer | Excellent for beginners | Tends crops, harvests, and delivers food ingredients to the kitchen. |
| Miner | Excellent for beginners | Digs out new areas, clears debris, and accesses buried resources. |
| Cook | Situational | Prepares meals at cooking stations, manages food storage and spice production. |
| Suit Wearer | Good (but demanding) | Works in any hazardous environment while consuming suit oxygen supply. |
Our recommendation: Start with Farmer. Farmers handle all food production from Mealwood farms to Bristle Blossom hydroponic setups. High Agriculture skill increases crop tending speed and prevents withering. Late game, they manage Grubfruit and Nosh Bean farms for +8 morale food recipes.
Avoid Suit Wearer as your first pick. Not a traditional class but a critical role — any Dupe with Exosuit Training can work in hazardous areas without oxygen concerns.
First Session Step-by-Step
Step 1: Learn gas management
Gases in ONI have realistic density — oxygen sinks below hydrogen, carbon dioxide pools at the bottom, and chlorine settles above CO2. You must design ventilation systems using Gas Pumps, Gas Filters, and Vents to route breathable air to living quarters while venting polluted oxygen through Deodorizers. Each gas has specific temperature and pressure properties that affect Duplicant comfort and machine efficiency.
This is the foundation. Spend your first 15-30 minutes getting comfortable with how gas management works before worrying about anything else.
Step 2: Head to Starting Biome
The temperate starting area contains Oxylite for initial oxygen, Mealwood seeds for food, and Algae for early Oxygen Diffusers. Temperature stays around 25-30C, which is comfortable for Dupes. Prioritize securing water access and building basic infrastructure here before expanding.
Clear the main content here before moving on. Everything teaches fundamentals you'll need later.
Step 3: Get Your First Upgrade
Look for SPOM System — it's the most accessible early upgrade. The Self-Powered Oxygen Module combines an Electrolyzer, Hydrogen Generator, Gas Pump, and Gas Filter in a self-sustaining loop. The hydrogen byproduct powers the generator, which runs the pumps and electrolyzer. A properly built SPOM requires zero external power and produces net-positive oxygen for 8-10 Duplicants.
Step 4: Understand pipe systems
Liquid and gas pipes form the circulatory system of your base, carrying water, polluted water, petroleum, and various gases. Pipes have a 10kg/s throughput limit for liquids, and bridges allow you to create priority junctions. Insulated pipes prevent temperature transfer, which is critical when routing hot petroleum past your farm tiles. Pipe overlaps and bridge direction mistakes are the number one cause of base flooding.
This is the system most new players overlook. Invest time here early — it pays off throughout the entire game.
Step 5: Push to Caustic Biome
A hot biome (40-50C) filled with Chlorine gas, Bleach Stone, and natural gas geysers. Chlorine kills germs, making it useful for sanitization rooms. The natural gas geysers here provide reliable fuel for Natural Gas Generators. Don't dig in without Atmo Suits.
Essential Mechanics Explained
gas management
Gases in ONI have realistic density — oxygen sinks below hydrogen, carbon dioxide pools at the bottom, and chlorine settles above CO2. You must design ventilation systems using Gas Pumps, Gas Filters, and Vents to route breathable air to living quarters while venting polluted oxygen through Deodorizers. Each gas has specific temperature and pressure properties that affect Duplicant comfort and machine efficiency.
pipe systems
Liquid and gas pipes form the circulatory system of your base, carrying water, polluted water, petroleum, and various gases. Pipes have a 10kg/s throughput limit for liquids, and bridges allow you to create priority junctions. Insulated pipes prevent temperature transfer, which is critical when routing hot petroleum past your farm tiles. Pipe overlaps and bridge direction mistakes are the number one cause of base flooding.
duplicant skills
Each Duplicant has innate attributes (Athletics, Strength, Creativity, Science, etc.) plus positive and negative traits like Diver's Lungs (+25% oxygen efficiency) or Narcoleptic (falls asleep randomly). The skill tree lets you specialize Dupes into roles like Rancher, Mechanic, or Rocketry. Morale requirements increase with skill points, so you need better food, decor, and recreation to keep skilled Dupes happy.
research tree
Research progresses through tiers using Research Stations (tier 1-2), Super Computers (tier 3), and eventually Interplanetary Research for space-age tech. Each tier requires different materials — basic research uses Dirt, advanced uses Water, and space research uses Data Banks from space missions. Prioritizing Farming and Temperature tech early prevents food crises and overheating disasters.
space exploration
Space exploration requires building rockets from modular components — nosecone, fuel tank, engine, cargo bay, and habitat modules. In Spaced Out!, you send rockets to nearby planetoids to establish satellite colonies for rare resources like Isoresin and Fullerene. Rocket automation with scheduling and fuel logistics is one of the game's most complex late-game systems.
Common Beginner Mistakes
1. Printing too many Duplicants early — each Dupe adds 100g/s oxygen demand and 1000 kcal/cycle food demand, and colony death spirals start from overpopulation before infrastructure is ready
2. Ignoring temperature management until everything overheats — by cycle 100, heat from machines and hot biomes will cook your crops and stress your Dupes if you haven't built cooling loops
3. Building Electrolyzers without proper gas separation — unfiltered output mixes hydrogen into your oxygen supply, which Dupes can't breathe and which can cause hydrogen buildup in living quarters
4. Not insulating the base perimeter — hot biomes at 70C will slowly heat your 25C starting area through regular tiles, killing Mealwood farms that die above 30C
5. Running generators without Smart Battery automation — continuously running generators waste fuel and dump excess heat into your base, creating both resource drain and cooling problems
First 5 Hours Checklist
- Understand gas management and pipe systems
- Choose Farmer as starting build
- Clear Starting Biome main content
- Acquire SPOM System or equivalent upgrade
- Reach Caustic Biome
- Build a SPOM (Self-Powered Oxygen Module) by cycle 30 — one Electrolyzer, two Gas Pumps, a Gas Filter, and a Hydrogen Generator in a sealed room provides oxygen for 8 Dupes with zero external power.
- Insulate your base perimeter with Insulated Tiles made from Igneous Rock (not Sandstone) to prevent heat bleed from hot biomes — temperature creep is the silent colony killer.
Tips for New Players
- Build a SPOM (Self-Powered Oxygen Module) by cycle 30 — one Electrolyzer, two Gas Pumps, a Gas Filter, and a Hydrogen Generator in a sealed room provides oxygen for 8 Dupes with zero external power.
- Insulate your base perimeter with Insulated Tiles made from Igneous Rock (not Sandstone) to prevent heat bleed from hot biomes — temperature creep is the silent colony killer.
- Meal Lice into Liceloaf at a Microbe Musher is your safest early food chain: it requires no water, no cooking skill, and provides enough calories until you set up ranching or farming.
- Never dig into Slime Biomes without Atmo Suits — Slimelung in polluted oxygen causes debuffs, and the Slime off-gasses polluted oxygen when exposed to regular atmosphere.
- Wheezeworts cool rooms by 12kDTU/s without power but consume Phosphorite as fertilizer. Place them in your farm or server room for passive cooling before you research Steam Turbines.
- Set up a permanent Carbon Dioxide scrubbing solution: either a Carbon Skimmer (uses water + power) or let CO2 pool at the bottom of your base and pump it to Slicksters, which convert it into oil.
- Smart Batteries should control every generator — set automation to turn generators on at 20% and off at 80% to prevent wasting fuel and overheating from continuous operation.
- Prioritize Athletics on all Dupes — movement speed affects everything. A Dupe with 20 Athletics completes tasks nearly twice as fast as one with 5, across all errands.
- Use Automation wires and sensors extensively: Thermo Sensors, Hydro Sensors, and Atmo Sensors let you build systems that self-regulate without manual intervention.
- Don't print more than 8 Duplicants until your food and oxygen systems are stable — each new Dupe consumes 100g/s oxygen and 1000 kcal/cycle, and overpopulation spirals fast.
Frequently Asked Questions
What is the best oxygen setup in Oxygen Not Included?
The SPOM (Self-Powered Oxygen Module) is the gold standard. Build one Electrolyzer in a sealed room with two Gas Pumps — one at the top for hydrogen, one at the bottom for oxygen. Route hydrogen to a Hydrogen Generator, which powers the pumps and electrolyzer. This setup is self-sustaining, requires only water input, and supports 8-10 Duplicants.
How do I manage temperature in ONI?
Early game, use Insulated Tiles (Igneous Rock) to seal your base from hot biomes, and place Wheezeworts in critical areas. Mid game, build an Aquatuner + Steam Turbine combo: the Aquatuner cools liquid by 14C per pass and dumps heat into a sealed steam room, where a Steam Turbine converts that heat into power. This deletes heat from your system permanently.
How many Duplicants should I have?
Stay at 4-6 Dupes for the first 50 cycles until your food and oxygen systems are stable. Expand to 8-12 once you have a SPOM and sustainable food (ranching or advanced farming). Going beyond 16 requires significant infrastructure. Each Dupe needs 100g/s oxygen and 1000 kcal/cycle minimum.
What should I research first in ONI?
Rush Insulated Tiles and Deodorizers in the first 10 cycles, then prioritize Meal Prep (Microbe Musher) and Basic Farming. Next, get Filtration (for your SPOM setup) and Smart Batteries. Temperature management tech (Thermo Regulators, then Steam Turbines) should come before cycle 80.
Is the Spaced Out DLC worth it?
Yes. Spaced Out adds multi-asteroid colonies, new biomes, radiation mechanics, and modular rockets. It fundamentally changes mid-to-late game progression by splitting rare resources across different asteroids, forcing you to build supply chains between colonies. The DLC also includes new critters, buildings, and the Data Bank research system.
What to Read Next
- Oxygen Not Included Builds — Optimize your build once you've learned the basics
- Oxygen Not Included Walkthrough — Full progression path
- Oxygen Not Included Tips — Advanced strategies for when you're ready
