Zoochosis reminds me heavily of the Mortuary Assistant -- you start your inspection of each enclosure by doing your chores feeding the animals, while also inspecting each of them for symptoms or indications of distress. The game does an okay job explaining what to do between entering the enclosure and identifying illness, but the handholding is abruptly cut off the moment mutants are thrown into the picture.
I spent several hours trying and failing different strategies, and I feel this qualifies me for one of the first basic guides on how to patch up your mangled giraffes and penguins!

This guide will be updated as I learn more, as well as when I gather instructional photos or videos to visualize what I'm saying here. Any feedback would be greatly appreciated so I can adapt this guide to suit as wide an audience as possible.

This game came out today as of writing this and it's the first game by this dev team, so cut it some slack. Bugs are and will be prominent for a while, but assuming Zoochosis gets some tender love and care, I'm sure it has the potential to be a top-notch game the devs can be proud of as a maiden voyage.

Starting out a new game is possibly the single most difficult part of the game, for a very simple reason:

YOU HAVE NOTHING.

Minimal resources for making different drugs means you have to be precise and almost perfect with every action you take. Luckily, the game seems to offer a few key milestones early on that I see as requirements before moving forward.


PREPARE YOUR FOOD IN ADVANCE.
The most important thing to remember is you only have one visit to the enclosure before the parasite reveals itself. You should not have to return to the train until you have completed everything you're able to without the stress of animals dying. When you're ready, start pushing the cart to the enclosure until you hear the phone ringing.

PICK UP THE PHONE.
This call is VERY important. The woman concerned about CJ will give you the code to his locker in the hub, which contains a floppy disk for the story and a PDA that will grant you the vaccines for the parasites. Once you've answered the call, continue. At this point I won't risk returning to the train, just in case the game decides I was close enough to the enclosure for Phase 1 to start.

GET TO WORK.
Push your cart to the enclosure and do EVERYTHING you can. This is what I affectionately refer to as Phase 1, the Investigation. Get every animal's temperature, test their aversion to sound, and feed them, collecting their feces after a while. Get every animal's blood that you reasonably can. Some may not be cooperative, but this early on it's not worth trekking back to make an ad hoc tranquilizer. If you can't get every blood sample, we'll return to it shortly.

ANALYZE YOUR BLOOD & CRAP.
Push the cart back to the train and insert the feces and blood samples, then hop on the computer and use the filters to diagnose your animals. Not all animals will show every symptom, but every symptom of the disease the enclosure has will be present at least once. You might have one penguin with a fever, one with an infected stool, one with infected blood, and one that freaks out when you yell in its general direction. Even though no individual has all the symptoms, all 4 of those in the same enclosure means all the animals that HAVE SYMPTOMS have the plague. Maybe there's no blood infection, or maybe no fever. Every animal with symptoms in the same enclosure have the same disease, and the ones without symptoms are clean. Curing the sick ones can wait a minute though...

When you begin to walk back towards the enclosure, the door will break and one of the animals will be waiting on the other side, mutated from the parasite. This marks the start of Phase 2: the Vaccination. DO NOT BOTHER TRYING TO HELP YET! Instead, run back to the train and flee to the hub!

COLLECT YOUR SUPPLIES AND COOK.
Returning to the room where your wife bangs on the door, you can pick up a TON of supplies from the mail slot to the right of said door. These are essential for your first enclosure, as without it you can't even guarantee having enough drugs to euthanize the mutant, let alone cure it! The resources are still scarce, so don't let the dozen or so bottles get to your head.
Get in the train and make a few tranquilizers. You should have at least one to guarantee you can collect blood mid-fight from a normal animal. Optionally, you can make one or two more to use on the mutant, if you aren't confident you can work under pressure or simply want to have a minute or two of certain safety. Don't worry about curing the sick animals until after the mutant has been dealt with.

THE BATTLE.
Time to engage the mutant! Your first goal should be to tranq a normal animal. Having a sleeping animal means you have access to blood for the vaccine. If you still haven't confirmed all the animals are clear for blood infections, be sure to tranq one that you haven't checked yet, so you can kill two birds with one stone. Collect two blood samples and run back to the train. If you brought extra tranquilizer darts for the mutant, now is the time to use them. If you shoot the mutant while sleeping, it will wake up and roar, then immediately go back to sleep and add the new tranq time on top of the old one. With two darts, you can buy yourself roughly a minute of peace.
In the train, create one of the vaccines for the parasite. It's important to know what disease your animals have, as there's a special vaccine to kill the parasite that only works on ones mimicking that disease. The plague parasite vaccine won't do anything on the mutant if the animals are showing symptoms of influenza. CREATING ONE OF THE VACCINES IN THE COMPUTER WILL GIVE YOU THREE DARTS. This is not explained anywhere, and only applies to the parasite vaccines. If you aren't sure about your aim, make another three with that second blood sample you collected. You will need to land three hits on the mutant to cure it.
With your new ammo, run back into the enclosure and start to vaccinate your mutant! If it is still asleep, the vaccine will immediately wake it, and the dart will instantly draw the mutant's attention to you. If you get charged, a safe place to hide is just inside the corridor. When the three hearts disappear, you should be safe to reload your dart gun and head back in. Keep at it until the three darts are sticking out of your mutant's butt and it turns back to normal!

WRAPPING UP THE ENCLOSURE.
Now that the threat is gone and the animals are safe, you are free to move back and forth between the train and enclosure without risk. Return to the train, create as many vaccines for the actual illness as you need, and immunize your animals. A popup will let you know when the enclosure is saved!

I'll keep this section short & sweet, as it's really just a less detail-oriented version of what we covered above. The main difference here is you should unlock the ability to create food for the mutants by adding meat into the original meal plan for the animals. This will turn the mutant back to normal for as long as you should need, or until you start to vaccinate it. As resources for drugs can be VERY tight, you may find it easier to feed the mutant as you return for Phase 2, so you can skip tranquilizers entirely and just take blood from the relaxed animals. Again, the moment you start to shoot darts into the mutant, it will return to its monster self and start to fight.
You should have more than enough resources to handle every enclosure from here on out! As you finish an enclosure, be sure to stop by the storage room and pillage whatever you can, because inevitably you'll miss a dart or want a little more breathing room, only to find yourself cutting it way too close on resources. It's a horrible way to lose, realizing that you don't even have the drugs to kill the animal, and that the only outcome is failure.

While Zoochosis certainly doesn't win awards for its comprehensive tutorials, the gameplay loop works, and mastering it can feel pretty dang rewarding! I once again encourage any questions, comments, or suggestions to be provided, as I'd love to foster this game's growth. Did I miss something, or make a mistake? Let me know!
I'm going to sleep now, as it's 3AM Eastern Standard and this game has already sucked away half of my planned sleep. Cheers!