How to unlock the Count Down from 47 achievement/trophy in Hitman 3

Agent 47 is a little tired after all of this killing.

In the Hitman games, Agent 47 is a killing machine at peak performance. It usually takes more than a couple of people to take him down in a fight, and even then, he is not an easy person to fight. However, at the end of Hitman 3, you can unlock a secret achievement by going down without outside help. This achievement is called Count Down from 47, and its description reads, “47 takes another nap.” Here is how to unlock the achievement or trophy in Untouchable.

When you start up the mission in the Carpathian Mountains, Agent 47 wakes up from a medically induced sleep. This is a hint that will come to help us later. Work your way through the entire level. Remember that you can kill any Providence members, and the train you are on is filled with them. Eventually, you reach the front of the train and find Arthur Edwards, your assassination target. A small cutscene will play, and he opens a suitcase with a serum in it.

The idea is you are supposed to use this syringe to kill Edwards, but you can actually use it on yourself. When Edwards walks away, standstill with the needle in your hand for 47 seconds. Eventually, Edwards will ask if you are having second thoughts. Press the button shown, and you will inject the serum into yourself and fall asleep.