Oxygen Not Included Review

By Terris Harned (NWOrpheus)

I never actually played Dwarf Fortress, so in some ways I’m a latecomer to the colony survival genre. I did play Gnomoria and Banished, and I reviewed Judgment: Apocalypse Survival early on in my career with OnRPG and MMOHuts. I’ve also logged a fair number of hours with Rimworld. It’s not a stretch to say that I have a reasonable amount of experience with the genre. As such, when I say that Oxygen Not Included (ONI) is by far my favorite colony survival game, you should pay attention.

There’s no one element of ONI that makes it excel above the others that I play; it’s the whole package. Perhaps I’m biased, as I purchased the title when it first hit early access on Steam in 2017, and I’ve watched it grow from a seedling into a beautiful flower. Whatever the case, I absolutely adore this fun little sandbox-in-an-asteroid game. Though my 162 hours of playtime is dwarfed by other players in the thousands, I love ONI just as much.

The story of ONI revolves around a trio of clones who find themselves in a small chamber in the center of an asteroid. How the clones came to be inside the asteroid is a mystery that the game teases and hints at. Suffice to say, it is your job to ensure that the clones, called duplicants (or dupes), survive.

To that end, your colonists will need food and water, a place to make waste after eating food and drinking water (preferably not the floor), and a place to sleep. You’ll also have to make sure that your dupes practice good hygiene and wash their hands after using the potty, or they’re liable to end up with a nasty case of food poisoning. Temperature also comes into play, as dupes that find themselves in environments that are too hot or too cold will find themselves stressed out and possibly prone to illness. And of course, you’ll need to make sure they have oxygen to breathe.

Before you worry about any of that stuff, however, you’ll have to select your starting asteroid and colonists. The latter is done at a sort of 3D printer that processes primordial goo into various useful things. On Cycle 1 you’ll have to select three duplicants to get your colony started, but every three cycles after that, you’ll be able to select from four different items. At least two seem always to be duplicants, but the other options can be a variety of useful items, from animal eggs to food to algae (used to produce oxygen).

It can take a minute to find a team that compliments each other, but it’s worth it.


Your starting duplicant selection can be fairly important. Thankfully, you can click the reroll button an infinite number of times on each of the three duplicants until you get a set you want to work with. Each dupe has at least one positive and one negative trait. There’s a huge selection of these, so I won’t list them all, but I recommend staying away from the ones that increase your hunger or make you have to use the restroom more often, at least in the early stages.

My favorite traits in the early game are ones that increase digging and building skills, since you’ll be doing these activities a great deal more than anything else at the start of the game. There are eleven attributes in Oxygen Not Included. Don’t worry if a duplicant doesn’t have great attributes across the board, as they will typically level up through usage and through the skill system, which I’ll cover a bit later.

The attributes, and what they improve, follow: strength, carrying capacity and tidying speed; construction, how fast things get built; machinery, how quickly machines are used; athletics, duplicant’s movement speed; science, research speed and skill point gain; cuisine, how fast food is prepared; creativity, the speed at which decorating jobs are done, such as painting or sculpture making; excavation, block removal speed and combat ability; medicine, medical care; agriculture, speed with dealing with plants; husbandry, how quickly the dupe tends to animals.

You might notice every single attribute in some way relates to how quickly you do something. This is because efficiency is the key in ONI. Every day your dupes use a certain amount of oxygen and food. You’ll want to make sure you’re utilizing your time as best as you possibly can.

The final thing you’ll notice is that each duplicant has between one and three interests. Interests reduce the morale requirements on the skill board, a feature which allows you to increase your dupes’ attributes and earn a snazzy hat associated with the skill.

Much like Team Fortress 2 players, those duplicants love their hats.


Skills used to be called jobs, but they changed the name along the way. Whenever you pick up a skill from the skill board system (accessed through the HQ/3D Printer), it increases the morale requirements of a duplicant. IE, the more useful the duplicant is, the higher their demands are. When a duplicant learns a skill that they have an interest in, however, there is a reduced morale cost, as it’s something the duplicant enjoys doing anyway.

Choosing duplicants that have interests that coincide with a single high attribute can be a great way to min-max. On the other hand, if you choose a duplicant with several interests you can make a nice well rounded colonist. It all depends on what you feel your needs are at the time.

Once you start the game, the first thing you’ll want to do is locate your water sources. Since each asteroid is randomly generated, unless you pick a seed you like to reuse, you’ll have to look around. Since so many things require water, like hand washing stations, you’re going to need to find where it’s located quickly. Building your bathrooms closer to water will reduce the time dupes spend going back and forth from the manual water pump to the bathroom, thus increasing your efficiency. Later on you’ll be able to research an automated water pump, which will alleviate this issue.

Oxygen Not Included is a game with a lot going on all at once. Thankfully, you can pause the game to look around and get your bearings, give commands, et cetera. There are also three speeds of play. I tend to spend the majority of my time in the game letting things run on the fastest speed, because I’m impatient. If I need to slow down and see how things are working, it’s nice to be able to do that though. Usually I’ll slow or pause the game when I’m going through the many different overlay panels, which are incredibly useful. It’s easier to show these to you than to tell you about them.

I also really enjoy the priority system in Oxygen Not Included, compared to some other colony sims. There are actually multiple levels with which you can prioritise as well. Each duplicant can have their own priorities set, from “avoid this task” which is an X to “do this first if it needs to be done” which is two up pointing triangles. Dupes will do tasks on the left side of the list first, and then move to the right, but will prioritize something that is marked high priority to the right of something that’s lower priority to the left.

I know it sounds somewhat complicated, but really it’s very intuitive as you get going in the game, and the game has a robust set of tutorial pop-ups that will help you along the way.

In this GIF you can see Abe will do care tasks before research, but he’ll do farming and then digging before he does either of those.


In addition to general priorities, individual tasks can be given priorities as well. For example, if I want to ensure that cooking tasks are done before cleaning tasks, I can set the microbe musher (a food creating station) to priority 8, and the cleaning tasks to priority 7. This helps make sure that things keep running smoothly without you having to micromanage your duplicants. Which is good, since you’re really not able to do so anyway.

If I had one complaint about Oxygen Not Included, it would be that crafting stations don’t have a “build to” as many similar games do. That is to say, I can’t go to the microbe musher and say, “make mush bars until you have 10”. I can tell it to make 10 bars, but if 2 get eaten while I’m making those 10, then I’ll only have 8. You can tell your dupes to make them forever, or at least until you tell them not to, but this can be fairly wasteful. Really though, this isn’t that big of an issue.

If you read my articles, you know it’s not often that I give scores of 4 or higher. Oxygen Not Included is an easy 4.5 out of 5 asteroids in my book. If it was the first colony survival game ever made, I would probably have given it a straight up 5, but with its charming aesthetic, its ambiance creating background music, engaging sound profile, near infinite replayability, customizable challenge level, well arranged user interface, and just damn good gameplay, it’s no wonder that ONI has such a large and engaged community of ardent fans. Klei continues to be a game studio that stands tall.


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