Containment
Contain the Citadel core.
Pacifist
Contain the Citadel core without killing any stalkers.
Citizen Escort
Don't let any citizens die when escorting them to the escape train.
Escape From City 17
Escape City 17 with Alyx.
The One Free Bullet
Finish the game firing exactly one bullet. Grenade, crowbar, rocket, and Gravity Gun kills are okay!
Elevator Action
Survive long enough to get on the parking garage elevator.
Attica!
Destroy the gunship in the hospital attic.
Watch Your Head!
Make it to the bottom of the Citadel's main elevator shaft in one piece.
Car Crusher
Use the cars to squash 15 antlions in Episode One.
Live Bait
Help Alyx snipe 30 enemies in Episode One.
Twofer
Defeat both antlion guards outside the White Forest.
Into the Breach
Help Griggs and Sheckley hold off the antlion invasion inside the mine shaft.
Defense of the Armament
Save the missile silo from the Combine offensive.
Meet the Hunters
Survive the Hunter ambush with Alyx.
Secondary Silo Secured
Secure the launch doors on missile silo 2.
Neighborhood Watch
Save all buildings outside the missile silo from destruction.
Pedal to the Metal
Beat DOG in a race to the White Forest base.
Gordon Propelled Rocket
Unlock the rocket launcher lambda cache in chapter Under The Radar.
Quiet Mountain Getaway
Survive the ambush at White Forest Inn.
Piñata Party
Find and break every web cache in Episode Two.
Cache Checker
Find every radar cache in chapter Under The Radar.
Get Some Grub
Squish every antlion grub in Episode Two.
Puttin' On a Clinic
Defeat the chopper in Episode Two without any misses.
Gunishment!
Destroy the Combine Autogun in the junkyard.
Hit and Run
Run over 20 enemies with the car in Episode Two.
Payback
Kill a Hunter with its own flechettes.
Acid Reflex
Kill an acid antlion worker.
Little Rocket Man
Send the garden gnome into space.
Grave Robber
Steal a Zombine's grenade.
Zombie-que
Use flares to light 15 zombies on fire.
Gnome Alone
If you are reading this achievement, Gabe Newell has successfully launched Gnome Chompski into space. If you did not also receive the achievement 'Manufacturing Ascent', Newell has abandoned his plans to shoot Noam Chomsky into space.
Giant Killer
Survive the rooftop strider battle in the ruins of City 17.
Hallowed Ground
No description
Keep Off the Sand!
Cross the antlion beach in chapter Sandtraps without touching the sand.
Singularity Collapse
No description
Plaza Defender
Survive the generator plaza standoff in chapter Anticitizen One.
Zombie Chopper
Play through Ravenholm using only the Gravity Gun.
Fight the Power
Shut down the supression device by disabling its generators.
Radiation Levels Detected
Get through the toxic tunnel under City 17 in Half-Life 2.
Warden Freeman
Survive the second turret standoff in Nova Prospekt.
What cat?
Break the mini-teleporter in Kleiner's lab.
Atomizer
Disintegrate 15 soldiers by throwing them into a Combine ball field.
Malcontent
Escape the apartment block raid.
Lambda Locator
Find all lambda caches in Half-Life 2.
Blast from the Past
Find the HEV Suit Charger faceplate in Eli's scrapyard.
Vorticough
Discover the hidden singing vortigaunt cave in chapter Water Hazard.
Follow Freeman
Gain command of a squad of rebels in the uprising.
Anchor's Aweigh!
Get the airboat.
Heavy Weapons
Get the airboat's mounted gun.
Trusty Hardware
Get the crowbar.
Zero-Point Energy
Get the Gravity Gun in Black Mesa East.
Defiant
No description
Counter-Sniper
Kill all of the snipers in City 17.
Barnacle Bowling
Kill five barnacles with one barrel.
Revenge!
Destroy the hunter-chopper in Half-Life 2.
Bug Hunt
Use the antlions to kill 50 enemies.
OSHA Violation
Kill 3 enemies using the crane.
Flushed
Kill an enemy with a toilet.
Where Cubbage Fears to Tread
No description
One Man Army
Destroy six gunships in Half-Life 2.
Two Points
Use DOG's ball to make a basket in Eli's scrapyard.
Targetted Advertising
Pin a soldier to the billboard in chapter Highway 17.
Submissive
No description
Think Fast!
Kill an Elite Soldier with his own energy ball.
Hack Attack!
Kill five enemies with a Manhack.
Conservationist
Kill five enemies with the same energy ball.
Bone Breaker
Kill 30 enemies with thrown physics objects.
Deadly Harvest
Kill an enemy by planting a hopper mine.
Hot Potat0wned
Kill a Combine soldier with his own grenade.