Here is the full list of all 27 Nobodies achievements.
Complete the Lab mission without leaving any evidence behind.
Dispose of the body in a bloody way.
Complete the Construction mission without leaving any evidence behind.
Incinerate the cabin, the gas station, and the body in Norrbotten.
Kill every character that can be killed.
Honestly, we're the monsters for letting you kill the dog.
Crush every car in the junkyard.
Test out every laboratory drug on the guard.
Hide the body in the water tank and then turn on the tap.
Get drunk three times on the train.
View the credits of the hospital's intranet.
Simulate a totally implausible suicide.
Cause the office worker in the hangar to overdose.
Finish the game without using the pager.
Complete every mission.
Complete the House mission without leaving any evidence behind.
Complete the Hotel mission without leaving any evidence behind.
Complete the Snow mission without leaving any evidence behind.
Complete the Hospital mission without leaving any evidence behind.
Complete the Junkyard mission without leaving any evidence behind.
Complete the Train mission without leaving any evidence behind.
Complete the Prison mission without leaving any evidence behind.
Complete the Museum mission without leaving any evidence behind.
Complete the Hangar mission without leaving any evidence behind.
Get lost in the woods.
Contact the fire department.
Take out the guard by giving him a lot (and we mean a LOT) of coffee.