Squish every antlion grub in Episode Two.
Jump 300 feet.
Accumulate 25000 heal points as a Medic.
Accumulate 1000 total kills.
Accumulate 10 turret kills with a single turret.
Successfully defend Dustbowl without giving up a capture.
Play in a game with seven or more players from your friends list.
Play a complete round with every class.
Continue playing to unlock this secret achievement.
Defeat the chopper in Episode Two without any misses.
Win Hydro without giving up a capture.
Play a complete game on every map.
Successfully defend Gravel Pit without giving up a capture.
Kill a Hunter with its own flechettes.
Get 25 headshots as a Sniper.
Beat all six Portal advanced maps.
Play through Ravenholm using only the Gravity Gun.
Escape City 17 with Alyx.
Don't let any citizens die when escorting them to the escape train.
Destroy the gunship in the hospital attic.
Help Alyx snipe 30 enemies in Episode One.
Survive long enough to get on the parking garage elevator.
Steal a Zombine's grenade.
Use the cars to squash 15 antlions in Episode One.
Contain the Citadel core.
Trick an opposing medic into healing you.
Get five revenge kills.
Set five enemies on fire in 30 seconds.
Win Well in 5 minutes or less.
Beat four Portal advanced maps.
Beat two Portal advanced maps.
Fall 30,000 feet.
Complete Portal.
Make the correct party escort submission position decision.
Do whatever it takes to survive.
Knock down a turret with another turret.
Survive the rooftop strider battle in the ruins of City 17.
Destroy six gunships in Half-Life 2.
Shut down the supression device by disabling its generators.
Kill all of the snipers in City 17.
Survive the generator plaza standoff in chapter Anticitizen One.
Get through the toxic tunnel under City 17 in Half-Life 2.
Kill five enemies with a Manhack.
Kill an enemy by planting a hopper mine.
Gain command of a squad of rebels in the uprising.
Break the mini-teleporter in Kleiner's lab.
Survive the second turret standoff in Nova Prospekt.
Kill a Combine soldier with his own grenade.
Use the antlions to kill 50 enemies.
Cross the antlion beach in chapter Sandtraps without touching the sand.
Kill 30 enemies with thrown physics objects.
Use DOG's ball to make a basket in Eli's scrapyard.
Acquire the fully powered Aperture Science Handheld Portal Device.
Get the Gravity Gun in Black Mesa East.
Destroy the hunter-chopper in Half-Life 2.
Get the airboat's mounted gun.
Get the airboat.
Get the crowbar.
Escape the apartment block raid.
Win 2Fort with a shutout.
Get five kills in a row without dying.
Help Griggs and Sheckley hold off the antlion invasion inside the mine shaft.
Run over 20 enemies with the car in Episode Two.
Find every radar cache in chapter Under The Radar.
Unlock the rocket launcher lambda cache in chapter Under The Radar.
Beat DOG in a race to the White Forest base.
Send the garden gnome into space.
Save all buildings outside the missile silo from destruction.
Earn bronze medals on all Portal challenges.
Earn silver medals on all Portal challenges.
Earn gold medals on all Portal challenges.
Win 20 games.
Disintegrate 15 soldiers by throwing them into a Combine ball field.
Detach security cameras from the walls.
Kill five enemies with the same energy ball.
Kill an Elite Soldier with his own energy ball.
Use flares to light 15 zombies on fire.
Kill five barnacles with one barrel.
Discover the hidden singing vortigaunt cave in chapter Water Hazard.
Find the HEV Suit Charger faceplate in Eli's scrapyard.
Kill 3 enemies using the crane.
Pin a soldier to the billboard in chapter Highway 17.
Kill an enemy with a toilet.
Find all lambda caches in Half-Life 2.
Make it to the bottom of the Citadel's main elevator shaft in one piece.
Contain the Citadel core without killing any stalkers.
Beat Episode One firing exactly one bullet. Grenade, crowbar, rocket, and Gravgun kills are okay!
Kill an acid antlion worker.
Find and break every web cache in Episode Two.
