This is a very unique and challenging colony sim that tip-toes the line between scientific realism and cute sci-fi game. Along with the typical game mechanics of balancing food, electricity, and building materials, it touches on concepts such as air pressure, thermodynamics, infectious diseases, and even the carbon cycle.

The game teaches these concepts so well, I'd even argue it's a great educational tool. Despite this, I have gripes about many unintuitive game mechanics:

* Polluted water produced by using toilets contains germs that you need to manage. Forcing the duplicants (the colonists) to wash their hands will prevent these germs from being spread to food. This is amazingly intuitive and realistic, but then come the oddities. There is a machine for cleaning Polluted water into regular water. However, this only makes the water usable again and does not kill the germs. Killing the germs requires a very complicated process that is largely unnecessary, due to additional quirks.

* Germs will spread to food through cooking, but beyond that they interact with the environment in very peculiar ways. You can turn contaminated water into contaminated oxygen, and it will spread through your colony at alarming rates. However, it turns out this is harmless since food poisoning in the air will not interact with the surfaces of your colony in any way (if the germ is slime lung, though, your duplicants can inhale it and bad things will happen). Similarly, a duplicant covered in germs can walk straight into your fresh water supply without spreading any germs to it. As far as I can tell, the only way to contaminate water is by mixing it with water or polluted water that contains germs. Which, by the way, can certainly happen and completely ruin an early run if you haven't figured out the bathrooms yet.

* Some things, such as polluted water and polluted dirt, emit polluted oxygen. Unless you're paying attention to the wording, you would think that means it contaminates oxygen by making it polluted. In fact, it's actually creating new oxygen. This can be exploited to generate oxygen from nothing, just by leaving polluted objects lying around.

There are many more strange mechanics and surprises that will leave you puzzled and looking through wikis and tutorials, or reloading a save because you massacred your entire colony. A few of these quirks have improved over the years of development (ie. some machines used to output liquids at a set temperature, allowing you to effectively delete heat). However, since the game is no longer in early access, I doubt the remaining issues will be addressed.

Very few games have affected my day to day life in the way that ONI has. When I use the A/C in the summer, I think about how it is blowing hot air out of my home instead of heating my hot water. When I take a shower in the winter, I think about the hot water going into the septic system instead of heating my home. One might even see it could be an excellent tool to help understand science, as long as you note the many quirks. I'm not going to lie, it's challenging, but if you're a fan of engineering games like Factorio it can be quite a fun challenge.

This is a very unique and challenging colony sim that tip-toes the line between scientific realism and cute sci-fi game. Along with the typical game mechanics of balancing food, electricity, and building materials, it touches on concepts such as air pressure, thermodynamics, infectious diseases, and even the carbon cycle. The game teaches these concepts so well, I'd even argue it's a great educational tool. Despite this, I have gripes about many unintuitive game mechanics: * Polluted water produced by using toilets contains germs that you need to manage. Forcing the duplicants (the colonists) to wash their hands will prevent these germs from being spread to food. This is amazingly intuitive and realistic, but then come the oddities. There is a machine for cleaning Polluted water into regular water. However, this only makes the water usable again and does not kill the germs. Killing the germs requires a very complicated process that is largely unnecessary, due to additional quirks. * Germs will spread to food through cooking, but beyond that they interact with the environment in very peculiar ways. You can turn contaminated water into contaminated oxygen, and it will spread through your colony at alarming rates. However, it turns out this is harmless since food poisoning in the air will not interact with the surfaces of your colony in any way (if the germ is slime lung, though, your duplicants can inhale it and bad things will happen). Similarly, a duplicant covered in germs can walk straight into your fresh water supply without spreading any germs to it. As far as I can tell, the only way to contaminate water is by mixing it with water or polluted water that contains germs. Which, by the way, can certainly happen and completely ruin an early run if you haven't figured out the bathrooms yet. * Some things, such as polluted water and polluted dirt, [i]emit[/i] polluted oxygen. Unless you're paying attention to the wording, you would think that means it contaminates oxygen by making it polluted. In fact, it's actually creating new oxygen. This can be exploited to generate oxygen from nothing, just by leaving polluted objects lying around. There are many more strange mechanics and surprises that will leave you puzzled and looking through wikis and tutorials, or reloading a save because you massacred your entire colony. A few of these quirks have improved over the years of development (ie. some machines used to output liquids at a set temperature, allowing you to effectively delete heat). However, since the game is no longer in early access, I doubt the remaining issues will be addressed. Very few games have affected my day to day life in the way that ONI has. When I use the A/C in the summer, I think about how it is blowing hot air out of my home instead of heating my hot water. When I take a shower in the winter, I think about the hot water going into the septic system instead of heating my home. One might even see it could be an excellent tool to help understand science, as long as you note the many quirks. I'm not going to lie, it's challenging, but if you're a fan of engineering games like Factorio it can be quite a fun challenge.