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.
Combat in Oxygen Not Included rewards knowledge over reflexes. Understanding how each mechanic works — and how they interact — is what turns a struggling player into a dominant one. New here? Start with our beginner's guide for the basics.
Core Combat Mechanics
1. 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.
Why it matters: This is the foundation of all combat. Everything else builds on this.
2. 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.
Why it matters: The most underrated mechanic. Players who master this early have a massive advantage.
3. 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.
Why it matters: Unlocks a new layer of gameplay depth once understood.
4. 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.
Why it matters: The tactical edge that separates average players from advanced ones.
5. 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.
Why it matters: The endgame optimization mechanic. Small improvements here compound into massive gains.
Mechanic Synergies
Understanding how mechanics interact is where real optimization happens:
gas management + pipe systems
Gases in ONI have realistic density — oxygen sinks below hydrogen, carbon dioxide pools at the bottom, and chlorine settles above CO2. When combined with pipe systems, liquid and gas pipes form the circulatory system of your base, carrying water, polluted water, petroleum, and various gases. This combination is the core of every effective build.
duplicant skills + research tree
Each Duplicant has innate attributes (Athletics, Strength, Creativity, Science, etc. Paired with research tree, research progresses through tiers using research stations (tier 1-2), super computers (tier 3), and eventually interplanetary research for space-age tech. This is why the tier list favors builds that leverage both.
space exploration as a Multiplier
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. This system amplifies everything else — the better your space exploration optimization, the more your other mechanics pay off.
Combat by Build
Each build approaches combat differently:
Researcher (S-Tier)
Combat approach: Parks at research stations full-time, occasionally operating telescopes for space data. Key equipment: Electrolyzer Primary mechanic: gas management
Researchers are essential early game and remain valuable throughout. Full setup in our builds guide.
Farmer (A-Tier)
Combat approach: Tends crops, harvests, and delivers food ingredients to the kitchen. Key equipment: SPOM System Primary mechanic: pipe systems
Farmers handle all food production from Mealwood farms to Bristle Blossom hydroponic setups. Full setup in our builds guide.
Miner (A-Tier)
Combat approach: Digs out new areas, clears debris, and accesses buried resources. Key equipment: Steam Turbine Primary mechanic: duplicant skills
Miners with high Excavation skill dig faster and access Hard Digging for Abyssalite and Obsidian. Full setup in our builds guide.
Cook (B-Tier)
Combat approach: Prepares meals at cooking stations, manages food storage and spice production. Key equipment: Aquatuner Primary mechanic: research tree
Cooks operate the Electric Grill and Gas Range to produce high-morale meals like Frost Burger (+6) and Berry Sludge. Full setup in our builds guide.
Suit Wearer (S-Tier)
Combat approach: Works in any hazardous environment while consuming suit oxygen supply. Key equipment: Solar Panels Primary mechanic: space exploration
Not a traditional class but a critical role — any Dupe with Exosuit Training can work in hazardous areas without oxygen concerns. Full setup in our builds guide.
Advanced Combat Techniques
Damage Optimization
- Match your equipment to your build's stat priorities
- Exploit gas management for maximum damage windows
- Chain pipe systems and duplicant skills for combo damage
- Use research tree to create openings
Survivability
- Learn enemy patterns before committing to attacks
- 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.
- Position using gas management to control spacing
- Save defensive options for guaranteed survival, not comfort
Boss Combat
Bosses test your understanding of every mechanic. See our boss guide for fight-specific strategies.
- Phase awareness — Most bosses change behavior at health thresholds
- Patience over aggression — One extra hit per opening beats dying to greed
- Build preparation — Swap gear and equipment for specific fights when needed
Common Combat Mistakes
- Button mashing — Committed attacks have recovery frames. Mashing locks you into animations.
- Ignoring pipe systems — This mechanic exists for a reason. Players who use it take significantly less damage.
- Wrong equipment for the situation — Check our weapons guide for situational picks.
- Not learning from deaths — Every death teaches something. If you don't know why you died, you'll die the same way again.
- Overcommitting — Trading hits works in Starting Biome but will get you killed in Space Surface.
More Oxygen Not Included Guides
- Oxygen Not Included Oxygen Not Included Overview
- Oxygen Not Included Best Builds
- Oxygen Not Included Tier List
- Oxygen Not Included Walkthrough
- Oxygen Not Included Beginner's Guide
- Oxygen Not Included Tips & Tricks
- Oxygen Not Included Weapons Guide
- Oxygen Not Included Boss Guide
- Oxygen Not Included Maps & Locations
- Oxygen Not Included Crafting Guide
- Oxygen Not Included Classes & Characters
Similar Games
If you enjoy Oxygen Not Included, check out these related guides:
- Stardew Valley Combat Guide — simulation game with similar mechanics
- Satisfactory Combat Guide — simulation game with similar mechanics
- The Sims 4 Combat Guide — simulation game with similar mechanics
