Kill an Elite Soldier with his own energy ball.
Make it to the bottom of the Citadel's main elevator shaft in one piece.
Beat DOG in a race to the White Forest base.
Find every radar cache in chapter Under The Radar.
Run over 20 enemies with the car in Episode Two.
Unlock the rocket launcher lambda cache in chapter Under The Radar.
Kill a Hunter with its own flechettes.
Steal a Zombine's grenade.
Win Hydro without giving up a capture.
Win Well in 5 minutes or less.
Play a complete game on every map.
Play a complete round with every class.
Kill a Combine soldier with his own grenade.
Pin a soldier to the billboard in chapter Highway 17.
Kill 3 enemies using the crane.
Kill 30 enemies with thrown physics objects.
Use DOG's ball to make a basket in Eli's scrapyard.
Find the HEV Suit Charger faceplate in Eli's scrapyard.
Get the Gravity Gun in Black Mesa East.
Discover the hidden singing vortigaunt cave in chapter Water Hazard.
Destroy the hunter-chopper in Half-Life 2.
Fall 30,000 feet.
Get the airboat's mounted gun.
Get the airboat.
Do whatever it takes to survive.
Knock down a turret with another turret.
Kill five barnacles with one barrel.
Win 2Fort with a shutout.
Accumulate 10 turret kills with a single turret.
Get five kills in a row without dying.
Trick an opposing medic into healing you.
Get the crowbar.
Escape the apartment block raid.
Acquire the fully powered Aperture Science Handheld Portal Device.
Help Griggs and Sheckley hold off the antlion invasion inside the mine shaft.
Defeat the chopper in Episode Two without any misses.
Send the garden gnome into space.
Save all buildings outside the missile silo from destruction.
Make the correct party escort submission position decision.
Complete Portal.
Jump 300 feet.
Beat two Portal advanced maps.
Beat four Portal advanced maps.
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.
Get five revenge kills.
Play in a game with seven or more players from your friends list.
Win 20 games.
Accumulate 1000 total kills.
Successfully defend Dustbowl without giving up a capture.
Successfully defend Gravel Pit without giving up a capture.
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.
Kill an enemy by planting a hopper mine.
Kill five enemies with a Manhack.
Kill five enemies with the same energy ball.
Use flares to light 15 zombies on fire.
Break the mini-teleporter in Kleiner's lab.
Play through Ravenholm using only the Gravity Gun.
Destroy six gunships in Half-Life 2.
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.
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.
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.
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 City 17 with Alyx.
Beat Episode One firing exactly one bullet. Grenade, crowbar, rocket, and Gravgun kills are okay!
Kill an acid antlion worker.
Squish every antlion grub in Episode Two.
Find and break every web cache in Episode Two.
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