Oxygen Not Included: Beginner's Guide & Best Tips

So you bought Oxygen Not Included. You're probably confused and your third colony just suffocated. I've been there.

Let me be real with you. This game is a bastard. It's gorgeous, it's clever, and it will absolutely shit on you for the first 20 hours. I've got over 800 hours in ONI, and I still have colonies that spiral into a death loop because I forgot a single pipe bridge was backwards. The learning curve isn't a curve — it's a vertical brick wall made of carbon dioxide and your own failed expectations.

But here's the thing: once it clicks, it clicks hard. There's no other game that makes you feel like a genuine genius for figuring out a cooling loop that keeps your crops from overheating on cycle 150. I've played everything from RimWorld to Factorio, and ONI is the only one that makes me actually write notes on paper. Real paper. Like a psychopath.

This guide is the stuff I wish someone had told me before I lost my first 12 colonies to heat death, starvation, and one particularly embarrassing incident involving an open water tank and a lot of piss. I'm going to skip the tutorial-level "press WASD to move" garbage. You're smart. The game isn't — it just pretends to be. Let's break its legs.

Why you're probably rage-quitting (and it's not your fault)

The game does a terrible job explaining its own systems. That's not a hot take — it's a fact. The in-game tutorial is a joke. It tells you to build an outhouse and an algae deoxidizer and then just... leaves you there. Meanwhile, your base is slowly filling with polluted oxygen, your dupes are peeing on the floor, and the temperature is creeping toward 40°C because you put your coal generator inside the base like the game suggested.

The three biggest walls new players hit:

• Oxygen runs out — Algae deoxidizers work fine for the first 30 cycles. Then your algae runs dry and you panic-build electrolyzers that overheat and dump hydrogen everywhere. Congratulations, your base is now a fire hazard.
• Heat kills everything — Every machine you build generates heat. The game doesn't tell you this in a way that matters. By cycle 80, your mealwood plants are stifled at 30°C and you're wondering why your food supply just died overnight. I lost my first successful base to a single coal generator that slowly cooked my farm over 40 cycles. I watched it die in slow motion.
• Plumbing is a nightmare — Liquids in this game have distinct properties. Water freezes at 0°C. Polluted water freezes at -20°C. Crude oil at -40°C. But they also need space to flow, and bridges don't mix contents, and if you don't understand priority flow you'll flood your base trying to set up a simple bathroom loop. I'm not kidding — I've seen people quit over toilet plumbing.

If you're feeling dumb because your colony keeps dying, stop. The game is designed to kill you until you understand how it works. It's not a skill issue — it's a knowledge issue. Every failure teaches you one piece of the puzzle. The trick is not repeating that same failure next run.

What you actually need to do in the first 10 cycles

Forget everything the game's tutorial told you. Here's the real start.

Day one, your three dupes need oxygen and food. But more importantly, they need a toilet that doesn't turn your base into a biohazard zone. Build an outhouse immediately — not because it's good, but because it buys you time. Build a wash basin near the outhouse. Put a storage bin for dirt near your printing pod. That's your first 30 seconds.

Now, dig to find a clean water source. Not polluted water — clean water. You'll need it for research and oxygen. If you don't see any within 20 tiles of your pod, you're screwed. Restart. Seriously. I wasted two hours on a map that had zero clean water within 40 tiles. Don't be me.

Your first research goal is Food Preparation for a planter box and mealwood. Mealwood is your starter crop. It needs no irrigation — just dirt and a temperature below 30°C. Plant at least 5 per dupe. That means 15 plants minimum for a standard start. Do this before cycle 5.

Your second research goal is Power Regulation. That gives you the manual generator, which is your only safe power source for the first 30 cycles. If you build a coal generator inside your base before you can handle the heat, you will die. I have the corpses to prove it.

Here's a timing order I've refined over 50 failed starts:

• Cycle 1-3: Outhouse, wash basin, research station, super computer. Dig a latrine pit below your base for early CO2 storage.
• Cycle 4-7: Planter boxes and mealwood. 5 per dupe. Put them in a separate room with a door — don't let dupes walk through the farm constantly.
• Cycle 8-15: Build your first electrolyzer setup — outside your main base, ideally in a dedicated room. Use a hydrogen generator to burn what you don't need. You'll need at least 1000g of water per second to feed one electrolyzer continuously.
• Cycle 16-20: Set up a bathroom loop with a sieve. This recycles 100% of your toilet water. You never need to pipe fresh water to a toilet again.

That's it. That's the first 20 cycles. Everything else is optional. If you have these four systems running — oxygen, food, power, toilets — you can survive to cycle 100 and actually start building something cool.

Expert tips that took me 300 hours to figure out

I'm going to skip the obvious stuff like "use airflow tiles" and "paint your floor out of granite." Here's the real shit.

Bathroom water loops are zero-loss. A lavatory outputs 11.7 kg of polluted water per use. A sieve turns that into 11.7 kg of clean water. There's no mass loss. You can build a perpetual loop: toilet -> sieve -> toilet. Add a small overflow tank for the water from sinks (which is extra) and you never need to touch your plumbing again. I ran one base for 500 cycles without ever adding water to the bathroom loop.

Heat deletion is real and you should abuse it. The game's physics engine has specific heat calculations. When you convert water to steam in a steam turbine, you delete roughly 90% of the thermal energy. This is the single most important exploit in the game. A steam turbine + aquatuner combo is the basis of every late-game cooling system. Steam turbines absorb heat from steam, turn it into power, and output water at 95°C. The aquatuner moves heat from your base into the steam. Once you understand this loop, you can cool entire planets. Before you understand it, you'll keep cooking your crops. This mechanic is similar to heat management in Factorio, but ONI punishes you way harder for getting it wrong.

Dupe selection matters more than you think. The starting three dupes you choose can make or break your first 50 cycles. Prioritize dupes without negative traits that affect movement speed or learning. Mouth breather is a death sentence for a new player — they consume 50% more oxygen. Anemic makes them move 20% slower. Narcoleptic will literally fall asleep on the job. Take the "boring" dupes with three positive traits and no negatives. That +5 to learning is worth more than a fun gimmick. I've restarted runs because my best digger was also a narcoleptic and kept passing out in poison gas.

Use automation early. Even on cycle 30, a single atmo sensor set to "above 500g" connected to your electrolyzer can save your oxygen system from running dry. A thermo sensor set to "above 25°C" connected to a fan can save your crops. Automation wires cost zero power to run. There's no reason not to use them. I didn't touch automation until cycle 200 on my first successful run, and I spent 100 cycles manually toggling generators on and off like a caveman.

Gasses have mass and weight. This is the most misunderstood mechanic. Oxygen sits above CO2. Hydrogen sits above everything. If your base is a single open room, you'll have a layer of hydrogen at the top, oxygen in the middle, and CO2 pooling at the bottom. Use this. Dig a deep pit below your base — 10-15 tiles deep — and all the CO2 will sink into it naturally. Slap a carbon skimmer at the bottom of that pit and your CO2 problem is solved until you get slicksters. I didn't do this for my first 100 hours. I was just building skimmers everywhere like an idiot.

Common mistakes that killed my colonies (don't be me)

I've made every mistake in this game. Here are the ones that killed me the most.

Building a coal generator inside the main base. You've been warned. It outputs 3,000 DTU of heat per second. That's enough to raise your base temperature by 1°C every 20 cycles. Combine that with two other generators and a refinery and you'll hit 45°C by cycle 60. Your mealwood dies at 30°C. I had a colony with 12 dupes, great oxygen, good food stockpile — and they all starved because I didn't check the temperature tab for 30 cycles. I watched their stress levels spike as they went from "well fed" to "starving" over three cycles.

Ignoring decor. This sounds like a luxury for new players, but it's not. Dupes with high stress break equipment, give bad orders, and occasionally vomit everywhere, which then turns into polluted oxygen, which then gets into your air supply. Keep decor above 20 in high-traffic areas. Paint your floors with carpet or granite tiles. Put a single paint job on your main ladder shaft — it costs 5 kg of raw mineral for +10 decor and covers a huge area. One dupe vomit due to a stress break can contaminate 30 tiles of clean water. I know because it happened in my best base and I didn't catch it for 10 cycles.

Expanding horizontally too fast. The game rewards verticality. A ladder shaft with fire poles going straight down is infinitely better than a giant horizontal base with multiple floors. Dupes can climb down 30 tiles faster than they can walk 10 tiles horizontally. Build tall and narrow. I spent my first 5 attempts building giant horizontal rectangles and wondering why my dupes spent half the day walking between the bathroom and the research station.

Using all your starting water for research. You need clean water for oxygen and farming. Research uses water too — about 50 kg per research point. You need about 800 kg of water for all basic research. That's fine — you get 10-20 tons in your starting pool. But if you also use that water for toilets (don't — use the loop), or oxygen (you will), you can drain your supply by cycle 60. I once ran out of clean water because I was too lazy to pipe it correctly and used 300 kg per cycle on toilets. The bathroom loop fix saved that base at cycle 72 when I finally noticed my oxygen supply was 30g per tile and dropping.

Not watching the temperature tab. The game has a temperature overlay. Use it. Turn it on every 10 cycles and look at your base. If you see any yellow or orange spreading toward your farm, act immediately. Insulate your farm with insulated tiles made of mafic rock (decent thermal resistance) or ceramic (best from the start). I have a personal rule: if the temperature tab shows anything above 28°C inside my base, I drop everything and fix it. That rule has saved more colonies than any build strategy.

FAQ — the questions I see in every new player thread

Q: Why is my base full of carbon dioxide?
A: You don't have a pit. Dig a 10-tile-deep hole under your base. CO2 is heavier than oxygen. It will sink into the pit naturally. Put a carbon skimmer at the bottom of the pit and set it to "below 2000g." Done. You can also ranch slicksters later — they eat CO2 and produce crude oil.

Q: How do I cool my base without a steam turbine?
A: You don't, really. Ice coolers are a trap — they use enormous power and produce polluted water. Ice temperature shift plates are a temporary fix. The real answer is thermal stress management: don't put hot machines in your base. Build them outside or behind insulated tiles. You can survive to cycle 150 without active cooling if you're careful. But eventually you need a steam turbine/aquatuner loop. That's the only renewable cooling system.

Q: What's the best food crop?
A: For early game, mealwood. For mid game, grubfruit (requires sulfur subduction or a ranch) or bristle blossoms (requires clean water and light). For late game, pepper bread from a farmer's table. Don't bother with mushrooms until you have a reliable slime source — they're good but the slime biome is dangerous for new players. I lost two dupes to slimelung before I ever harvested a single mushroom.

Q: How many dupes should I take?
A: I usually take every dupe that arrives in the printing pod until I hit 8-10. More dupes means more work gets done, but also more resource consumption. 8 is a sweet spot for learning. You can sustain 8 dupes on 40 mealwood plants and one electrolyzer. After 10, you need more advanced life support. I don't go above 12 until I have an SPOM (self-powered oxygen module) and a reliable food source.

Q: Why did all my plants die?
A: Check the temperature. They die at 30°C if they're mealwood. Check the atmosphere — they need oxygen or CO2 depending on the crop. Check for stifled status. If the tile they're planted in is too hot or too cold, they stop growing. This is the number one killer of new player farms, including all three of my first successful runs.

Q: Do I need to build a hospital?
A: No. It's a waste of space unless you're playing on max difficulty. Immobile dupes recover in their bedroll. Slimelung is a risk but it's manageable with exosuits in the slime biome. I built a hospital exactly once, used it zero times, and then converted it to a barracks. But I still think about it sometimes.