This guide obviously is full of spoilers. I suggest you to finish the game once by yourself to prevent any spoilers. Which will not have any effect on your completion time.
It will most likely take 20–25 hours to 100% this game.
There are multiple endings which will make you finish the game more than 10 times but know that you can rewind your save and continue from previous days.
Please don't forget to thumbs up if this guide helps you in any way.

Day 7:

• First list of the Priest is given

Day 8:

• Hooded man gives the Purple Potion

Day 12:

• First list of the Gravedigger is given

Day 13:

• Second list of the Priest is given

Day 18:

• Third list of the Priest is given

Day 19:

• Witch comes and tells you to kill the fisherman

Day 20:

• Alora's nightstand

• Second list of the Gravedigger is given

Day 23:

• Cannibal attack (If you have treated him, your run ends here)

Day 24:

• Obtain the candle

So far,
If you are into the priest questline, you are going to get the blue candle
If you are into the witch questline, you are going to get the green candle
If you have rejected both of them, you are going to get the white candle

Day 27:

• Obtain the green potion

Day 28:

• Cure Thomas with the green potion

Day 29:

• Cure Marianne with the green potion

• Thank you, doc!

Treat your first patient

• Careless

Miss 3 anomaly in a day

• Savior

Max out your reputation

• Paranoid

Drink 2 laudanum when there are no anomalies

• Licensed to Kill

Kill a patient

• Criminal

Kill 7 patients

• Small price for Salvation

Kill a patient after Day 24

• Breaking Bad

Complete one of Gravedigger’s lists

• Merchant of Death

Complete both of Gravedigger's lists

• Blind Confidence

Untick the lamp for a single night

• Closer look

Buy the magnifying glass in Day 9

• Listen carefully

Buy the stethescope in Day 17

• Lovecraftian doctor

Fisherman are introduced in the 15th day. If you don't treat them, they will come back with being more infected. Treat a level 3 fisherman to get this achievement. I suggest you to do this in the Priest run since you are already supposed to not heal any of them. If you see a level 3 fisherman, treat him. This will probably cause you to die but you can just restart the day.

• Medical virtuoso

Heal a patient instantly with a cocktail

• Oops

Kill a patient instantly with a cocktail

• Ticket to escape

Cure Thomas in Day 28 with the green potion that's been given by the little girl in 27th day.
This will be required to get 2 different endings. See:

• Ending: Escape The Island with Thomas - Alora Rescued
  
• Ending: Escape The Island with Thomas - Alora is Left Behind

• Hard choice

Don't give the green potion from day 27 to Thomas. Instead give it to Marianne in 29th day.
This will be required to get 2 different endings. See:

• Ending: Escape The Island with Marianne - Alora Rescued
  
• Ending: Escape The Island with Marianne - Alora is Left Behind

• Ending: Dragged into the Abyss

After you get the blue candle in Day 24, simply set the candle out. You'll die and get the achievement in a couple seconds.

• Ending: Out of Mind

Let you sanity reach 0

• Ending: My Honey Pie

The Cannibal comes to you 3 times before attacking you at Day 23. If you treat him every time he stops by, you'll get the achievement but this will end the run

• Ending: Imprisoned

Kill too many patients to get imprisoned by the police. Don't let the reputation reach 0, this will lead to another achievement.
I don't know if a certain number of patients need to be killed but if you kill one patient each day (treat 4 patients for each kill, so your reputation will not collapse) the sheriff will imprison you in the Day 10.

• Ending: Burnt to ashes

Let your reputation drop down to 0
You can get this most early in the Day 3. Just kill every patient you see and you'll get this achievement.

• Ending: Bankrupt

Lose all your money
Killing patients will result in a fine. While keeping your reputation above zero and your kill count below 10, make your money get to negatives. You also need to ran out of medicines so be extravagant.
When you have no money to buy new medicines, the Sheriff will visit you to end your run.

• Ending: A new cycle begins
  
• Ending: Fleeing evil, becoming prey

If you complete all three lists of the Priest and manage to get to the 30th day, you'll be given two choices at day 30. Chose each to get these two achievements. Getting the blue candle in day 24 means you are in the right path.

• Ending: Blinded by Lust
  
• Ending: Cursed to Eternity

If you kill every fisherman from Day 19 to end after the witch tells you to, you'll be given two choices at day 30. Chose each to get these two achievements. Getting the green candle in day 24 means you are in the right path.

• Ending: Escape The Island with Thomas - Alora Rescued
  
• Ending: Escape The Island with Marianne - Alora Rescued
  
• Ending: Escape The Island with Thomas - Alora is Left Behind
  
• Ending: Escape The Island with Marianne - Alora is Left Behind
  
• Ending: Drowned in the Depths. - Alora drowned with you
  
• Ending: Drowned in the Depths. - Alora is Left Behind

There is one dilemma and one trilemma in the game:

1. Stay with Alora / Refuse her at Day 20
   
2. Cure Thomas / Cure Marianne / Don't cure any of them

Each combination gives one achievement, 6 in total.
Getting the white candle in day 24 means you are in the right path.

NOTE: You have to ignore both the Witch and the Priest to get these endings. They will lock you onto their own achievements.

• Clock's Just a Decoration

Treat a patient with less than a second remaining. You should use the last medicine as soon as the timer hits 0:03. It'll time perfectly.

• Do No Haste

Hit the timer 2:00 by bonuses.


1st Note: Even if you one shot a patient, you only gonna get a +0:10 bonus after calculating the time lost to treat the patient. So forget about looking at the book. Memorize the symptoms. Avoid +6 Vital & -5 Digestive medicines to prevent allergies.

2nd Note: +1 doses give +0:05, +2 doses give +0:15 and +3 doses give +0:30 seconds bonus. Useful information to know that, after you give a +3 after a +2, you are going to get a total of +0:45 bonus which is essential to get this achievement. If a patient comes to your office with a -2 status and you give +2, +2, +3 in order you are going to get a full minute bonus.

• Doctor's Marathon

Basically keep the timer alive for 10 minutes straight

• Emergency Care

You need to fully heal 5 patients in two minutes. You have just enough time to two shot every patient to get it.

• Level Up

Treat 50 patients with 100 xp acquired

• Full HP

Earn 100 hearts.

• Dr. Speedrun

Kill the first patient

• A Little Bit of This, a Little Bit of That...

Kill a patient with alternative drugs

• Allergic to Mistakes

Kill a patient with a dose that they are allergic to

• Doctor of the Year

Treat 50 patients in Do No Harm mode.
You don't have to fully heal them.