The game features a sizeable amount of game Departments, which I will devide into categories as they will not all function the same way.

In this section I will cover the support departments. Note that these Deparments are meant to complement other Departments so therefore there are really no metric to judge their difficulty. However, some tricks related to this Departments can be used to streamline patient care.

This will likely be the first Support Department you will ever invest in as it is necessary to support most Specialized Departments. Running Radiology itself is not very hard at all. However, keep in mind that you need to have a certain number of rooms according to the size of your hospital. It is recommended to build Radiology for both outpatient/inpatient and only for inpatient as the inpatient are more likely to have a need for it.

Basic Radiology: X-Rays, CTs, MRIs and CAGs:

X-Ray Room
Once you start up your emergency clinic, you're bound to get at least one patient that shows their contused hand/chest/leg/foot/arm and says: "Is it broken, Doc?"
This is where the X-Ray comes in. All you have to do is reserve some space for the big Xray Room and a waiting room. Then just hire a decent tech and you got yourself your first piece of Radiology equipment.
Indications:
-Emergency Clinic
-Basic Orthopeady
-Traumatology to an extend (Traumatology DLC)
-DID to an extend (DID DLC, for lung findings)
-Barium Swallows for General Surgery (got to find that fistula somehow)

CT Room
The first of the expensive scanning doughnuts, this device will be a livesaver in most departments, as they sometimes will need more than a quick X-Ray or Blood test to figure out what's inside.
Indications:
-Organ Scanning
-Internal Medicine
-General Surgery
-Advanced Orthopeady
-Neurology to an extent
-Cardiology to an extent
-Traumatology to an extend (Traumatology DLC)

MRI Room
The most expensive of the doughnuts, this will never be used unless Neurology or some other department wants to use them, usually Neurology.
Indications:
-Advanced Neurology
-Advanced Orthopaedy (for muscles)
-Decent use by Cardiology

CAG Room
The half eaten scanning doughnut, this will never be used unless Cardiology or some other department wants to use them, usually Cardiology.
Indications:
-Advanced Cardiology (for vessels)

Advanced Radiology: Cardiography, Sonography and Neuroscan:

Sonography Room:
The first of the advanced Radiology rooms, this little device is worth keeping in your hospital as sometimes all is needed is a bit less diagnosing juice.
Indications:
-Advanced Orthopaedy (for bursae)
-General Surgery to an extend

Cardiography Room:
This advanced Radiology room will be a lifesaver for most departments when a quick ECG is not available (Heart Monitoring). It can also have advanced usage for more advanced Radiology techniques needed by some departments.
Indications:
-Advanced Cardiology (Echo for looking at the heart)
-Most departments where Heart Monitoring is not available in the hospitalization (quick ECGs for finding heart rate anomalies)

Neuroscan Room:
The most expensive of the advanced Radiology rooms, this will never be used unless Neurology or some other department wants to use them, usually Neurology.
Fun fact: This room dependencies are exclusively associated with Neurology, although it is part of the advanced Radiology rooms. This means when setting it up, you will have this room belong to Neurology.
Indications:
-Advanced Neurology (usually for advanced eye examinations such as Tenometry or Perimetry)
-Internal Medicine to an extend (got to find those hallucinations from poisonings somehow, with an EEG)

This will likely be the second Support Department you will ever invest in as it is necessary to support some Specialized Departments. Running the Medical Labs itself is not very hard at all. However, keep in mind that you need to have a certain number of rooms according to the size of your hospital. It is recommended to build Medical Labs for both outpatient/inpatient and only for inpatient as the inpatient are more likely to have a need for it as more samples get processed from these patients.

Medical Labs: The Samples of Truth
The first step in complex diagnoses begins in the Medical Labs. Its recommended contents depends on the department, but it's best you squeeze them all in, just to widen your investigations.

Indications:
-Trying to differentiate between bacterial and viral tonsilitis
-Trying to differentiate the fungus on your patient's toe
-Amongst many others...

Another Department that is not very hard to run at all. However it comes with their own little kwirks:
-Pharmacies built must be big enough to whitstand full patient releases. Alternatively, you can build more than 1 Pharmacy if you are aiming for either realism or lack the space to build a big enough Pharmacy. If you can not handle the patient flow you will loose money from these patients discharged that need a prescription refill.
-Gift Shops work mostly the same way. They should be big enough as to not have visitors leave without purchasing gifts, otherwise you will loose the income they generate.
-This department well optimized serves as a good complementary money maker.
-Service Office allows you to have a janitor manager (allowing janitors to be assigned to specific rooms within their departments).
-Study Rooms are where staff can undergo staff training of skills.
-Cafeterias are a good alternative to the individual department common rooms.

Understanding how hiring works and which tratis can be removed via studying.
Hiring any personnel works as following:
-The higher their age, the more base salary they will ask for
-The higher their starting rank the more salary they will ask for, this means its cheaper to hire a lower rank candidate with better traits then lvelling them up to max rank than hiring a maxed out rank candiate. All hired candidates will never age anyway so the higher their rank usually the older they will be.
-Creating a character is a good custom investement (costs 10.000 dollars/per character) if you can afford it since they will start at the lowest posible rank depending on the role they are being created for. You are able to select their traits (2 green and 1 red, unless you are using mods that alter character creation processes). You can rename any character at any time by clicking on the pencil icon on their character card.
-The presence of the "Loyal" green perk will impact how much they ask for because this perk nerfs by 20% upon promotion the initial salary. This means at max rank a candidate will ask 20% less salary than a similar candidate with the same age.
-There is an option that is cheap and convenient to see all perks during hiring.
-Usually the more green perks a staff candidate has the better they will perform.
-The study room has a chance to remove most red perks such as:
-Slow Learner
-Hedoinist
-Germophobe
-Depressed
-The study room may have a chance to remove the following red perks:
-Slow
-The study room is unable to remove the following red perks:
-Hard Worker
-Fast Metabolism
-The remaining red perks are still undergoing testing as to fit in the above categories.

Pathology should be by far the smallest department you will ever want to build. No one likes to loose patients so you basically should have the bare minimum for the department to be open. That is 1 doctor and 1 nurse per shift, a small autopsy room and a small cold room. Running a succesfull hospital barely means the department will ever get used. It really only makes money if the worse happens to your patients (death). Its worthless if you are playing with the option "Patients can die" disabled. I say the department should be as mnimalistic as possible because if no autopsies are being done you are essentially just paying 4 salaries (2xdoctors; 2xnurses; for both day/night shifts).

I was extremely conflicted on whether I should place ICU on the Specialized Departments section of the guide or in the Support Departments section of the guide. In the end, I decided to place it in the latter. Here is why:
-ICU only takes cases with confirmed diagnosis that collapse. However, there is a workaround to this if you do not want to send a patient to your Trauma Center because it is either full or some other reason (like say you suspect the patient might be highly contagious). All you have to do is select a random diagnosis but not treat it, after admnistering the treatments for what is causing the collapsing sympthoms. Cancel all examinations so you dont get a wrong diagnosis message. If this is done correctly you should have a patient transferred to the ICU instead of the Trauma Center. This is extremely handy and therefore I recommend you build a large enough ICU unit in your hospital.
-Other ICU uses include major surgery patient control (Traumatology, Cardiology, General Surgery, Neurology especially) will benefit more for a higher level of care than their Specialized HDU department. The only excepton to this rule are Orthopedic surgeries and Neurology eye surgeries. This also enables the patient to get priority over any HDU patients if a surgery queue exists in a Department.
-The ICU is one of the 2 areas of hospitalization immune from outbreaks (DID DLC required for this mechanic). The other area is the DID Isolation Ward.
-Overall, running a ICU unit is a medium to hard affair. This is because of the number of cases from every single speciality available in the game having a chance to land there and because of the many variations the same illness has in the game.

I was extremely conflicted on whether I should place Emergency on the Specialized Departments section of the guide or in the Support Departments section of the guide. In the end, I decided to place it in the latter. Here is why:
-Emergency TC (Trauma Center) takes cases that come via ambulances (helicopter too, if they exist in a Traumatology DLC scenario hospital). It also takes any cases that collapse without a confirmed diagnosis from any department/area.
-The other area of interest is an Observation Ward that has many uses included to, but not limited to: Observation of complicated cases to free up clinic doctors for other pacients, admittance of long waiting patients to ease up clinic doctors work and administration of certain treatments for certain deparment illnesses to free up beds in the department specific wards and admittance of stabilized patients with confirmed diagnosis and treated to ease up on specialized departments ward space (the latter only works for light cases such as simple fractures, for example). Is it therefore recommended to build a large enough Observation ward to use it to its fullest potential.
-The ICU and DID Isolation Ward are the only 2 areas of hospitalization immune from outbreaks (DID DLC required for this mechanic). This makes it so Emergency is harder to manage if a DID patient that is considered contagious is not transferred to a "safe" area within the given timer (as they will by then start the Epidemic Outbreak event).
-Overall, because of this reasons, I consider Emergency to be the hardest Support Department to run in this game.

The bread and butter of any hospital. For these I will start ranking them up from the lowest to highest difficulty department in my opinion. Do note there are several ways to reach a final diagnosis. One is by exclusion and other by inclusion:
-Exclusion: Running exams/tests to exclude a particular diagnosis.
-Inclusion: Running exams/tests to confirm a particular diagnosis.
Both methods are valid to achieve the same result.

This department is responsible for illnesses related to the musculoeskeletical system (bones, muscles, bursaes, nerves, etc...). It is and behaves much like in real life. Collapse symthoms take a while before becoming dangerous so surgeries in this department can safely be considered low priority considered to other departments. Orthopaedy surgeries should have the lowest priority of all surgical Departments (luckily they only go as far as one, amongst the possible complications).

Department Dependencies:
Radiology: very high (X-Ray for fractures, MRI for muscle lesions, USG for bursae lesions, CT needed very rarely for bone weakness illnesses like Osteomalacia).
Medical Labs: average (mainly for bone weakness illnesses like Osteomalacia).

For the game simplicity, General Surgery deals with endocrine, urinary tract and abdominal injuries. In real life, however this is a broad term for many illnesses. The collapse timers here are generous enough. However, this department is higher in difficulty due to the number of illnesses that can lead to collapse in the game. General Surgery surgeries should have a higher priority than Orthopaedy ones (luckily they only go as far as one, amongst the possible complications).

Department Dependencies:
Radiology: very high (Barium Swallow X-Ray for Fistulas, MRI/CT/CT enterography for deep tissue injuries, USG/Transelastography USG for superficial tissue injuries).
Medical Labs: high (for a vast amount of hidden sympthoms: Sampling and more can be used to find them).

For the game simplicity, Internal Medicine deals with ear, nose and pulmonary injuries. In real life, however this is a broad term for many illnesses. The collapse timers here are even less generous than in General Surgery. However, this department is even higher in difficulty due to the number of illnesses that can lead to collapse in the game.

Department Dependencies:
Radiology: very high (X-Ray for lung findings, MRI for lung findings, CT for ear and nose findings).
Medical Labs: very high (Blood test for poisoning findings confirmation or ruling them out, other tests to rule out other department illnesses).

I decide to rank DID next on this list, not because it is necessarily harder than the previous 2 Departments but because of how it works in this game. Infectious deseases focus is on illnesses that affect the whole system and have some degree of risk for contagion. In real life it functions quite the same.
There are some mechanics that make this department stand out amongst the others like epidemic outbreaks and "safe" zones. In the game there are only 2 areas that are considered safe to avoid the epidemic outbreak debuff consequences. One is the ICU and the other is the DID Isolation Wards.
That being said, this department is really more annoying than difficult which is why is ranking so high in difficulty on this list. I would go as far as saying this is one of the end-game departments.

Department Dependencies:
Radiology: average (again mainly for lung findings).
Medical Labs: very high (for samples to confirm or rule out DID diagnosis).

Now we arrive at the top 3 of the most harder Specialized Departments to run in this game. And for me, I choose Cardiology. Much like in real life, Cardiology in this game deals with circulatory and heart related illnesses. Collapse timers are extremely unforgiving and most of the illnesses will require HDU hospitalization. Excluding surgeries, that as mention before, should be stabilized and rush to the ICU as to give them priority over other less complicated cases (luckily they only go as far as one, amongst the possible complications).

Department Dependencies:
Radiology: very high (Angiography for vessel imaging, Cardiography for ECG heart monitoring, Cardiography for heart echo, CT and MRI for heart organ scanning).
Medical Labs: high (for samples to confirm or rule out Cardiology diagnosis).

Ah yes, now we arrive at Traumatology. One of the 2 Departments that can have cases that go as far as needing 4 surgeries. Not only 90% of the clinic cases will require some form of hospitalization here but you will also have to deal with the most unforgiving collapse timers ever present in this game. The caviat being some of the diagnosis if caught on time can simply be treated in a clinic setting and sent home. Traumatology is, just like in real life, a Department that deals with everything from traumatic injuries to burn injuries, poisonous animal bites, etc...Needless to say any surgical case from this Department should be immediately rushed to an ICU unit for surgery once stabilization is complete.

Department Dependencies:
Radiology: very high (CT, X-Ray mainly for gunshot wounds, MRI secondly for locating possible injuries that require surgery).
Medical Labs: average (biopsy for burn tissue findings, urine sampling for bite poisoning deyidration, blood test for bite poisoning).

And lastly we have the infamous Neurology Department, the Grim Reaper of my main hospital. No other department has a higher mortality rate than this one. But why, you may ask? Neurology in this game deals with head and eye injuries. Unlike in real life, that only deals with head injuries. Neurology is a can of worms. It can go as far as being as easy as running a clinic and then you will get an infamous Penetrating trauma-Head that requires 3 surgeries within the same in-game hour. It can quickly go from 8 to 80. I would not say their surgeries should have higher priority than Traumatology but just about the same (excluding eye surgeries, these should have the same priority as Orthopaedy ones, because most eye related illnesses in the game have way more forgiving collapse timers, or aren’t considered to be a collapse high priority illness). If you get those infamous Neurosurgery cases you better pray to God they survive to the stabilization process, the first surgery, the surgical complications that may happen or the subsequent surgeries if they happen to need them. Collapse rating is generally on par with Traumatology as how fast the timers are before the collapsing sympthoms become a major problem (if untreated). Needless to say, this is another Department where surgical cases should be stabilized then rushed to the ICU for surgery (the only exception to this rule are eye surgeries that have slightly above priority over Orthopaedy ones).

Department Dependencies:
Radiology: very high (CT and MRI mainly for locating possible injuries that require additional surgeries, Neuroscan EEG (to locate possible surgical complications). Tenometry and Perimetry Neuroscans (to locate some non hazardous symptoms).
Medical Labs: average (testing for rulling out other departments diagnosis, CSF sampling to confirm diagnosis, peritonial fluid sample to confirm diagnosis).

Let me know if this guide has helped you understand a bit better how the game works, help you decide which departments to aim for after the mandatory ones, if there are any innacuracies here do not hesitate to point them out to me in the comments section (so I can correct them). New tips to improve this guide are also welcome. I hope you enjoy reading my guide as much as I enjoyed making it. Thank you for taking the time to read & give feedback. Stay healthy and happy managing :)

Beginner tip: You can view your hospital information via the stats window located at the bottom left of your screen, next to the current department big icon. By selecting the pencil icon you can rename your hospital from the default "Annonymous Hospital".