Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Treasure! (10 points): Unlock first container.
It Was An Accident (10 points): Kill first minion.
Self-Defense (15 points): Kill 10 minions.
Duress (20 points): Kill 20 minions.
Just Experimenting (10 points): Used Health Syringe for the first time.
I Can Stop Anytime (20 points): Used 20 Health Syringes..
You've Wasted Your Life (5 points): Idle for five minutes.
Would You Like To Know More? (20 points): Find your first Asylum File.
Who Is The Jigsaw Killer? (15 points): Find your first Patient File.
Darwin Would Be Proud (20 points): Died once.
Kill Or Be Killed (30 points): Killed a Collared Minion with a collar detonation.
Give Me Five! (10 points): First kill with a Mannequin Arm.
Homerun (10 points): First kill with a Bat.
Sometimes It Sticks (10 points): First kill with a Nail Bat.
Cleaning Up (10 points): First kill with a Mop Handle.
Pipe Dream (10 points): First kill with a Pipe.
Surgeon (10 points): First kill with a Scalpel.
Penetrated (10 points): First kill with a Syringe.
You've Been Served (10 points): First kill with a Table Leg.
You'll Need This Afterwards (10 points): First kill with a Crutch.
Grave Digger (10 points): First kill with a Shovel.
Lights Off (10 points): First kill with a Table Lamp.
Hatchet Job (10 points): First kill with a Hatchet.
Fire Hazard (10 points): First kill with fire.
Splitting Headache (10 points): First kill with Scissors.
Say Hello To My Little Friend (10 points): First kill with a Gun.
Wait For The Boom (10 points): First kill with an Explosive Mine.
Whoops! (10 points): First kill with a Stun Mine.
Choked Up (10 points): First kill with a Gas Mine.
I'm In Charge (10 points): Fought first NPC.
Curb Stomp (10 points): Stomped first Minion to death.
Merciless (20 points): Stomped five Minions to death.
Forced Entry (10 points): Unlocked first door.
Locksmith (20 points): Unlock 5 locked doors.
Professional (50 points): Unlock 20 locked doors.

Additionally, there are eleven secret achievements:

It's A Trap! (40 points): Complete Reverse Bear Trap.
What Was That?!? (5 points): First encounter with Pighead.
Hit And Run (40 points): Release Jennings from his Trap.
Damaged Goods (40 points): Release Amanda from her Trap.
Absent Parent (40 points): Release Melissa from her Trap.
Aphasia (40 points): Release Oswald from his Trap.
Eager Student (40 points): Release Obi from his Trap.
Born Victim (40 points): Release Jeff from his Trap.
Violence Begets Violence (40 points): Kill the Pighead.
Cost of the Truth (100 points): Complete Game using Truth Door.
Never Truly Free (100 points): Complete game using Freedom Door.