Episode 5 of Season 3 is a stream that opens on the game's "Automation Upgrade" notes, then loads the BasketCase3 colony where Episode 4 left it, with the new bedroom half built. The stream goes into germs, a strange liquid in the water, a set of liquid filters, and finally a sealed room of natural gas generators. By the end it is Cycle 53, nineteen duplicants are alive, the generators are making some power, and food is running short.
Mercury in the water
The first job is pumping the rest of the polluted water into the tank being converted. A pump is moved closer to the ladder so the duplicants can reach it, and then something odd shows up in the pipes. "Why is there mercury in my water? That's awkward." The answer, for now, is another big project: a separate tank lower down, where everything that is not water can go.
The beds in the new bedroom are assigned, and the commentary decides to dig a second floor of beds below it. Its floor is swapped for tiles that do not block gas, "so that way the oxygen that I have up in here" can drift down without vents of its own. Research goes to medicine, described on screen as producing "medicine to cure most basic diseases."
A germ problem
A look at the germ overlay shows trouble. "Oh, we have lots of problems with germs... immune system's a problem." The med-beds carry a warning, "Medical building outside Med Bay," and nobody seems to know what a med bay is. The commentary reads up, rebuilds the room with medical beds and a toilet, and still cannot get it to count: "I don't know how to make a medbay, it's a mystery."
Hand washing is the next try. Wash basins go up in a hallway, and the game's panel shows they are used by duplicants passing in one chosen direction, which is news: "that is not something I realized." Later a plumbed sink goes in near the dirty part of the base, set so duplicants wash on the way back. "There you go, wash your hands. Perfect."
Sorting the liquids
The water line gets its own fix. One liquid filter keeps the clean water going to the tank, a second sends polluted water off to the polluted tank, and anything else "will just pour out onto the ground in this room." Once it is built, the polluted water that was sitting in the way pours down into its new space. Mercury still shows in a pipe under the big water tank.
Meanwhile the farm is too warm. The commentary reads a range of 10 to 30 degrees for the plants and calls it "just a little bit too hot here," and a "Food shortage" alert comes up and stays for the rest of the stream. Some plants want chlorine, and there happens to be chlorine in one of the lower caves.
Natural gas power
Power keeps running short, so research turns to Fossil Fuels. There is natural gas in a cave below the base, and the plan is to wall it in behind an airlock, pump it out and burn it. "I haven't really tried to approach this before, so I don't really know what to expect."
Gas pumps go in, and filters split the natural gas from the chlorine, which is vented down to the plants that want it. Two Natural Gas Generators are built in a narrow room, with a pipe and vent for the hydrogen. The generators' panel cycles through "No Gas Intake," "No Gas Output," "Insufficient Resources" and "Generator Idle." When the output finally runs, it turns out to be carbon dioxide, piped down into the room for the other leftover liquids.
Then polluted water starts collecting. The game's own panel says natural gas generators "leak polluted water." The commentary had not planned on it: "That wasn't part of my plan." An extra airlock keeps it from pouring down, and duplicants are set to mop.
Where it ends
A broken gas pipe is patched and a Carbon Skimmer is placed, still waiting on copper ore. "What a mess. I'll have to redesign this whole thing later." The generators are running, with one still idle, maybe because its output pipe is already full, which is left to fix next time. New duplicants are available, food is short, and no research is selected.