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

Helping Hand (20 points): Revive 50 incapacitated Survivors.
Field Medic (20 points): Heal 25 Survivors with a first aid kit.
Pharm-assist (20 points): Give pain pills to 10 Survivors.
My Bodyguard (15 points): Protect any Survivor from an attacking Infected 50 times.
Dead Stop (10 points): Punch a Hunter as he is pouncing.
Cr0wnd (30 points): Kill a Witch with a single headshot.
Untouchables (30 points): No Survivors take damage after contacting the rescue vehicle.
Drag and Drop (20 points): Rescue a Survivor from a Smoker's tongue before he takes damage.
Blind Luck (20 points): You or another Survivor take no damage after being vomited on by a Boomer.
Akimbo Assassin (30 points): Survive an entire campaign using only pistols.
Hero Closet (10 points): Rescue a Survivor trapped in a closet.
Hunter Punter (10 points): Shove a Hunter off of a pinned and helpless Survivor.
Tongue Twister (20 points): Free yourself from a Smoker who has grabbed you with his tongue.
No Smoking Section (15 points): Kill 10 Smokers as they are pulling helpless Survivors.
101 Cremations (20 points): Set 101 Infected on fire.
Do Not Disturb (20 points): Sneak past all Witches in a campaign without disturbing one.
Man vs Tank (30 points): Single-handedly kill a Tank.
Tankbusters (20 points): Kill a Tank without it dealing any damage to a Survivor.
Safety First (30 points): Play an entire campaign with no Survivors taking friendly fire damage.
No-one Left Behind (20 points): Beat a campaign with all 4 Survivors.
Unbreakable (30 points): Finish a campaign without ever being healed.
Witch Hunter (20 points): Kill a Witch without any Survivor taking damage from her.
Red Mist (20 points): Kill 1000 Infected with a mounted machine gun.
Pyrotechnician (20 points): Blow up 20 Infected in a single explosion.
Zombie Genocidest (20 points): Kill 53,595 Infected.
Dead Giveaway (10 points): Heal a fellow Survivor when your own health is below 10.
Stand Tall (20 points): Survive a campaign without being incapacitated.
Zombicidal Maniac (30 points): Survive any campaign on Expert.
What Are You Trying to Prove? (35 points): Survive all campaigns on Expert.
Nothing Special (30 points):...