Oxygen Not Included

This game makes you feel like a genius and an idiot.
Forcing you to deal with an increasing volume of pee is a genre-advancing feature.
As we were taught in video game school : " easy to get, hard to master "
It's an unfortunate thing to say, but I think a lot of game studios are probably happy this doesn't have mass appeal because that would mean less half ass games with crap DLC and more high quality games worth playing that has to stand against this bad boy. ONI is definitely not for everyone, and in fact... I see few people actually play the game throughout and to the end. It requires patience, research, critical thinking, and a lot of anger. Most of the physics present in ONI are very realistic and force you to get a general understanding of how temperature works and pressures, etc. The game is inherently designed for thinkers/engineers, because those are the only people who would draw satisfaction from such madness. Usually these kind of games are niche and with absolute poop graphics, but ONI is one of the most good locking management games out there.
This game starts with acting like its cute and rewarding and pretty easy. Everything looks and feels so lovely and after 2 or 3 hours of gameplay it lets you know "nope your cleaned water isn't clean, it's full of germs which gives your colony a slow but unavoidable death". Yes, you can solve this puzzle but when you face it the first time it's probably way to late. It forces you to get over your base, where you put so much time and love. You have to study the game on youtube and the Steam forums. Then you come back, confident, create a germ-killer, you are unbeatable at this game! You play it for like 5-10 hours. Then.. the next problem arrives. I love the way the game just cascades complexity at you and almost every solution you come up with to the current problem creates a new problem or resource bottleneck somewhere down the line.
Everything in ONI has byproducts. In most craft/simcity style games, you need 1 wood 1 fiber to make an axe, use an axe to get more wood, 10 wood makes a plank, 2 planks and one iron makes a board, etc. In ONI, 10 wood makes a plank AND sawdust. Which builds up and becomes a problem over time. It's that little bit of polluted water the generators make, that little bit of CO2 the dupes breathe out, that little bit of heat that EVERYTHING makes, in ONI you craft and unlock better craftables to make things more efficiently just like every other game, but you ALSO have to deal with the long term problems that everything you've done so far has created. It is a subtle change to the gameplay loop but it makes the game so much more interesting. Complex and detailed system games are my favorite. When a game gives me the ability to actually think and create a scientific solution or at least do something that lets you feel like you invented something, that is the best feeling ever.
I think this is one of those games that's really fun to figure out on your own because it's almost like a roguelike but for RTS. You definitely learn from your failures, and pretty quickly. And failing isn't really presented as this big terrible thing, though you will definitely get attached to your little peeps. If you've played Fallout Shelter or something similar, it's very similar to that in look and feel, but there are about a million more ways to build your little colony. I think there's fun in exploring, but if you're failure/risk averse, then a How to Get Started tutorial won't ruin the experience.
This might get me burned, but I found Oxygen Not Included much more engaging and creative than Factorio. Both deal with managing systems, but where ONI's concept is colorful and varied, Factorio's is one simple idea multiplied a million times over. If ONI is a chess set, Factorio is more like a huge game of checkers. Thanks to the large amount of different and interconnected aspects of the simulation, ONI can keep the problems and solutions fresh well into the endgame. It also somehow manages to find that thin line of giving you just enough information that it feels like you're finding the solutions by yourself, not following a manual. Your solutions probably won't be perfect, but that's the fun part. In many games there is only one way to do something. In ONI there are many and people are constantly finding new ones. Some are better than others but you can do it plenty of ways.
The complexity and how the many systems interact with each other are the best part of the game, and unlike Factorio, having to manage these systems by necessity made me much more engaged and invested in what I was building. To me having bathrooms, handwashing etc made the game that much more engaging because it fed into the core gameplay loop, how to manage your resources, inputs, outputs and waste products while keeping everything balanced. In most other games, bathrooms are just a thing you build, but in Oxygen not included, bathrooms are a thing you design. How you get renewable water into your bathrooms, how to dispose of the germy waste water, and how if you work out the math the whole loop is actually beneficial bc it's water positive so you can easily make it a closed loop system as long as you handle the germs.
Having problems that initially seem small but slowly pile up into a catastrophe actually highlights the brilliance of the simulation. The key thing is nothing about those disasters are random. There's no Randy to randomly f**k you over. Every disaster that happens is some problem with your design that you can build a solution to. That to me is a level of control and skill I found lacking in Rimworld, because a lot of times the challenge comes from the scenario the story throws at you, rather than your own ability to design a proper base.
I really like the spaghetti. Smashing liquid and gas pipes all over the place, tying them together with some cables and running 5 different conveyor systems through your base. And all of that just to get pissed when you have to build 14 bridges to get the next pipe through that. But it still works. Oni is the most organized chaotic thing in my entire life. I love it.
This game ruins your experience over and over. For me it's an drug addiction: everything is fine in the beginning, then you can't stop, then your only thought is "i will f*** you back!". But you wont. And if you think at some point after suffering hours of hours you are "good", just check youtube for some automation-grid-farms that you don't even barely understand. If you expect having fun in this game in your first 100 hours playtime you are so wrong my fellow friend! The dev-teams keeps you staying positive for the first 2 hours, just right before it's too late for a steam refund!
10/10

Love this game but I am not smart enough for it so I usually go about 100 cycles and then reset

A really solid game overall, I really enjoy it.
However, I only bought it because they promised, "All future updates will be free, no more DLC".
Then they went back on that and started releasing a bunch of mediocre DLCs.
I don’t think that’s a promise you should be able to just walk back on.
Anyways, it's still a fun game, even if I feel a bit cheated.

Yeah, it’s alright.
Only consumed 9,224 hours of my life so far, which is roughly a third of my existence since release. Take that as you will.
I still don’t have all the achievements, not because they’re hard, but because I’m too busy building highly optimized piss dungeons and other crimes against duplicant dignity. I’ve beaten the game multiple times, but instead of chasing Steam achievements, I keep inventing my own questionable goals. Things like transporting an entire asteroid cluster into one spot on the starting rock, or running 500-critter farms without turning my PC into a space heater.
Jokes aside, this game is my zen. It’s cute, stressful, logic-based nonsense that feels like coding inside Photoshop while physics actively judges you. Every system has three other systems quietly waiting to collapse if you forget about heat, gas pressure, fluids, pathing, morale, bladder levels, or tantrums.
And the story arc? Brilliantly, existentially dark as hell. It sneaks up on you between bathroom breaks and oxygen crises and then casually reminds you how small, expendable, and doomed everything is.
If you like weird, adorable, brutally deep survival/base-building games where NPC bathroom schedules matter and where some players go so far as to build a computer inside the computer game, absolutely play it.
I’ve invested an embarrassing number of days of my life into this, so take my opinion with a grain of salt.
But also… yeah. It’s really good.

If you are not willing to spend most of your time initially watching video's online and reading the built in/online wiki I repeat this game is not for you. I was not aware of this before going in and I severely underestimated how complex this game is. ONI is one of a kind. There is no competitor that can come close to its management simulation. The atmospheric aspects and the many other layers, which are all connected to each other and therefore productivity or survival are great and this game could easily be a 10/10, especially because it is the pioneer in this field. But to make it a 10/10 experience it has to be played with mods. The basic version doesn't include many quality of life things, that mods can add. Mods also add so much content of buildings or UI. Due to the Steam Workshop support mods are great to install, but still tedious to search and find them as well as go over the struggle of a new patch and identify broken mods. Steam Workshop support is great though.

i saw markiplier play this game a many years back and decided to pick it up then. i have yet to put it down since. i have like 4 games TOTAL in my steam library, and this is the only game that i play at all. i adore this game! its so cute! its so charming! and it so much fun to problem solve for theres lil dummies lmao. im still looking for another colony management game the matches the amazingness of this game but i've yet to find one.
1000/10 would recommend

If you're the kind of player who thrives on depth, complexity, and the thrill of solving problems with increasingly elegant systems, Oxygen Not Included might be your next obsession. After 1700 hours, I can say without hesitation: this game has earned every minute.

Depth That Never Runs Dry
What looks like a quirky space-colony sim quickly reveals itself as a brutally intricate simulation of thermodynamics, fluid dynamics, gas exchange, agriculture, industrial automation, psychology, and even rocket science. And yet, it’s all packed into a charming, side-scrolling aesthetic with expressive Duplicants and satisfying sound design.

Even after thousands of cycles across multiple colonies, I'm still refining my designs, optimizing layouts, and discovering new strategies. There's no “one solution” — just more refined ones.

Engineering Playground
You’re not just surviving; you’re building systems. Water loops, oxygen production, heat management, food chains, power grids, automation, and late-game interplanetary logistics — this is a game where planning matters, and poor choices 100 cycles ago can come back to melt your base.

Mistakes teach. Recovery is a puzzle. Mastery is satisfying.

Endless Replayability
Every asteroid type demands new thinking. Traits, biomes, geysers — all randomized. You’re never playing the same game twice. Want a relaxed experience? Play Terra and build at your own pace. Want a challenge? Start on Rime and deal with the cold. Or try modded asteroids and explore community-curated chaos.

Systems Nerd Heaven
If you enjoy games like Factorio, Dwarf Fortress, or RimWorld, but crave more simulation and fewer guns, this is your game. ONI is about processes. It’s a colony sim where how you do something is often more important than what you do. That’s a rare design choice — and it's beautifully executed.

Minor Critiques
The early game can feel like a trap for new players who don’t understand heat, gas stratification, or resource scarcity.

Performance can drop in large colonies with lots of automation and piping.

There’s no hand-holding — but the Wiki and community are incredibly helpful.

Final Verdict: 10/10
Oxygen Not Included isn't a game you play. It's a game you inhabit. It's a slow-burn obsession for systems thinkers, tinkerers, and masochists who enjoy watching colonies implode because they forgot to vent CO₂. It’s also one of the most rewarding games I’ve ever touched.

1700 hours in, and I’m still asking: Can I make it better this time?