Kill 30 enemies with thrown physics objects.
Kill an enemy by planting a Hopper Mine.
Kill five enemies with a Manhack.
Kill a Combine Solider with his own grenade.
Kill 5 enemies with the same energy ball.
Kill an Elite soldier with his own energy ball.
Steal a Zombine's grenade.
Use flares to light 15 Zombies on fire.
Escape the apartment block raid.
Break the mini-teleporter in Kleiner's lab.
Get the Crowbar.
Kill 5 Barnacles with one barrel.
Get the Airboat.
Get the Airboat's mounted gun.
Discover the hidden singing Vortigaunt cave in chapter Water Hazard.
Destroy the Hunter-Chopper in Half-Life 2.
Blast from the Past
Find the HEV Suit Charger faceplate in Eli's scrapyard.
Get the Gravity Gun in Black Mesa East.
Use DOG's ball to make a basket in Eli's scrapyard.
Play through Ravenholm using only the Gravity Gun.
Kill 3 enemies using the Crane.
Pin a soldier to the billboard in chapter Highway 17.
One Man Army
Destroy six gunships in Half-Life 2.
Keep Off the Sand
Cross the Antlion beach in chapter Sandtraps without touching the sand.
Use the Antlions to kill 50 enemies.
Kill an enemy with a toilet.
Survive the second turret standoff in Nova Prospekt.
"Radiation Levels Detected"
Get through the toxic tunnel under City 17 in Half-Life 2.
Survive the generator plaza standoff in chapter Anticitizen One.
Kill all of the Snipers in City 17.
Fight the Power
Shut down the supression device by disabling its generators.
Survive the rooftop Strider battle in the ruins of City 17.
Find all lambda caches in Half-Life 2.
Watch Your Head!
Make it to the bottem of the Citadel's main elevator shaft in one piece.
Contain the Citadel core.
Contain the Citadel core without killing any Stalkers.
Use the cars to squash 15 Antlions in Episode One.
Survive long enough to get on the parking garage elevator.
Help Alyx snipe 30 enemies in Episode One.
Destroy the gunship in the hospital attic.
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
Beat Episode One firing exactly one bullet. Grenade, crowbar, rocket and Gravgun kills are okay!
Kill an acid Antlion Worker.
Get Some Grub
Squish every Antlion Grub in Episode Two.
Find and break every web cache in Episode Two.
Into the Breach
Help Griggs and Sheckley hold off the Antlion invasion inside the mine shaft.
Hit and Run
Run over 20 enemies with the car in Episode Two.
Puttin' On a Clinic
Defeat the Chopper in Episode Two without any misses.
Find every radar cache in chapter Under the Radar.
Gordon Propelled Rocket
Unlock the Rocket Launcher lambda cache in chapter Under the Radar.
Pedal to the Metal
Beat DOG in a race to the White Forest base.
Little Rocket Man
Send the garden gnome into Space.
Save all buildings outside the missile silo from destruction.
Kill a Hunter with its own flechettes.
Acquire the fully powered Aperture Science Handheld Portal Device.
Do whatever it takes to survive.
Make the correct party escort submission position decision.
Fall 30, 000 feet.
Jump 300 feet.
Beat two Portal advanced maps.
Beat four Portal advanced maps.
Vanilla Crazy Cake
Beat all six Portal advanced maps.
Earn bronze medals on all Portal challenges.
Earn silver medals on all Portal challenges.
Earn gold medals on all Portal challenges.
Accumulate 10 turret kills with a single turret.
Get five revenge kills.
Hard to Kill
Get five kills in a row without dying.
Master of Disguise
Trick an opposing medic into healing you.
With Friends Like these...
Play in a game with seven or more players from your friends list.
Win 20 games.
Accumulate 1000 total kills.
Win 2Fort with a shutout.
Win Well in 5 mins or less.
Win Hydro without giving up a capture.
Successfully defend Dustbowl without giving up a capture.
Successfully defend Gravel Pit without giving up a capture.
Head of the Class
Play a complete round with every class.
Play a complete game on every map.
Accumulate 25000 heal points as a Medic.
Set five enemies on fire in 30 seconds.
Disintegrate 15 soldiers by throwing them into a Combine ball field.
Gain command of a squad of rebels in the uprising.
Get 25 headshots as a Sniper.
Detach security cameras from the walls.
Knock down a turret with another turret.
Put the can in the trash
Hit the Trashcan Cop with the can.
Escort Gregori safely through the church cemetery
Where Cubbage Fears to Tread
Defend Little Odessa from the Gunship attack.
Destroy the Citadel's reactor core.
Defeat both Antlion Guards outside the White Forest.
Meet the Hunters
Survive the Hunter ambush with Alyx.
Destroy the Combine cannon in the junkyard.
Quiet Mountain Getaway
Survive the ambush at White Forest Inn.
Secondary Silo Secured
Secure the launch doors on missile silo 2.
Defense of the Armament
Save the missile silo from the Combine offensive.