Oxygen Not Included is a game by Klei, the people that made Don’t Starve (another one of my favourite games). It’s still in the early development stages but very playable, nothing’s particularly buggy. I found that the overall playstyle was very unique. It’s a sandbox game with some pretty interesting lore, but that’s all in the works still so it’s a little incomplete at this stage.

Before you even enter the little world, you get to pick your “duplicants”. Each one has different skills, strengths and weaknesses, and some can be game changing if you don’t know what to look for. You start off with three duplicants and a strange portal that they call a printing pod. The game says that you’ve crashed into a meteorite, but need to keep the dupes alive before you can explore more.

What do you do?

The main actions are digging, researching and building. You can “mine” the materials around you to slowly expand your little dwelling, and you can set up a research station to allow your dupes to build more advanced things... but it’s not as simple as that. There are a lot of forces working against you.

The most interesting part about this game is the very realistic take on gases, pressure, temperature and disease. You have a variety of elements that behave mostly in the same way as their real-world counterparts. Trying to keep the air pressure, temperature, oxygen levels and germs all at livable amounts can prove very difficult. And they weren’t kidding, oxygen really isn’t included. It can be pretty damn hard to find sometimes.

Gases

The main properties of the gases are their element, pressure and temperature. In your inner base you’re looking for oxygen, at around 23°c, with a pressure of 1000g/block. It’s a lot to control, especially when your dupes are breathing CO2 into the mix or worse… farting (I learned the hard way that the “flatulent” trait was definitely one to avoid). Luckily you can sort things out fairly easily. The CO2 sinks, so you can let it accumulate at the bottom of your base and sort it out from there.
Other gases have some nifty advantages, but also some disadvantages. Chlorine gas is unbreathable and super toxic, but it kills any germs. This makes it great for disinfecting. Hydrogen can be used for energy, as can natural gas (the dupes fart natural gas, so I’m sure someone’s made a Sims-style hell dungeon full of flatulent dupes powering the colony).

Temperature

You begin the game in a “bubble” with a temperature of approx. 23°c. It’s pretty important to stay inside this bubble until you can start to regulate temperature because once you’ve removed the many blocks insulating you, the heat starts to seep in. Temperature can affect plant growth, element state, germs and animals. Generally high temperatures are undesirable, as they’re very easy to create but extremely difficult to remove. Cooling is often a problem, especially early game.
If you dig a little deeper though you’ll find that there are often very subtle ways of controlling the temperature. Everything you can build, you can generally (within reason) choose what material it’s built of. Choosing highly conductive materials could be a blessing or a curse, depending on what you want to happen. For example, there is a buildable block called “insulating tile”. It does a pretty good job of insulation, but why not take it a step further and make your insulation blocks out of a naturally insulating material? Early game this can be as simple as avoiding metals, but later game you can start using plastics.

Germs

Germs in the game seem to be in the pretty early stages. When I started playing there were only two, but they have increased it to 4 now. Each one is found in different environments, and can infect in different ways. The two that I started with were food poisoning and slimelung. Food poisoning is produced mainly by the lavatories. Not including some way for the dupes to disinfect after using them means the germs will spread into their food, water supply, and even the air. Slimelung is found in the slime biomes. It spreads in a similar way, and is generally released when mining slime blocks. In general, food poisoning becomes a problem when the dupes eat contaminated food, and slimelung a problem when they breathe contaminated air.

The game often requires the use of a lot of trial and error. There aren’t many tutorials on it, so it’s fun to keep trying new and different things, trying to keep in mind the physics and chemical properties of different materials. Most importantly, don’t let your dupes die. It’s really sad, and they just kinda lie there and make you feel really guilty.