Save the missile silo from the Combine offensive.

Secure the launch doors on missile silo 2.

Survive the ambush at White Forest Inn.

Destroy the Combine cannon in the junkyard.

Survive the Hunter ambush with Alyx.

Defeat both antlion guards outside the White Forest.

Destroy the Citadel's reactor core.

Defend Little Odessa from the Gunship Attack

Escort Gregori safely through the church cemetery

Hit the trashcan cop with the can.

Put the can in the trash.

Knock down a turret with another turret.

Detach security cameras from the walls.

Get 25 headshots as a Sniper.

Gain command of a squad of rebels in the uprising.

Disintegrate 15 soldiers by throwing them into a Combine ball field.

Set five enemies on fire in 30 seconds.

Accumulate 25000 heal points as a Medic.

Play a complete game on every map.

Play a complete round with every class.

Successfully defend Gravel Pit without giving up a capture.

Successfully defend Dustbowl without giving up a capture.

Win Hydro without giving up a capture.

Win Well in 5 minutes or less.

Win 2Fort with a shutout.

Accumulate 1000 total kills.

Win 20 games.

Play in a game with seven or more players from your friends list.

Trick an opposing medic into healing you.

Get five kills in a row without dying.

Get five revenge kills.

Accumulate 10 turret kills with a single turret.

Earn gold medals on all Portal challenges.

Earn silver medals on all Portal challenges.

Earn bronze medals on all Portal challenges.

Beat all six Portal advanced maps.

Beat four Portal advanced maps.

Beat two Portal advanced maps.

Jump 300 feet.

Fall 30,000 feet.

Complete Portal.

Make the correct party escort submission position decision.

Do whatever it takes to survive.

Acquire the fully powered Aperture Science Handheld Portal Device.

Kill a Hunter with its own flechettes.

Save all buildings outside the missile silo from destruction.

Send the garden gnome into space.

Beat DOG in a race to the White Forest base.

Unlock the rocket launcher lambda cache in chapter Under The Radar.

Find every radar cache in chapter Under The Radar.

Defeat the chopper in Episode Two without any misses.

Run over 20 enemies with the car in Episode Two.

Help Griggs and Sheckley hold off the antlion invasion inside the mine shaft.

Find and break every web cache in Episode Two.

Squish every antlion grub in Episode Two.

Kill an acid antlion worker.

Beat Episode One firing exactly one bullet. Grenade, crowbar, rocket, and Gravgun kills are okay!

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.

Use the cars to squash 15 antlions in Episode One.

Contain the Citadel core without killing any stalkers.

Contain the Citadel core.

Make it to the bottom of the Citadel's main elevator shaft in one piece.

Find all lambda caches in Half-Life 2.

Survive the rooftop strider battle in the ruins of City 17.

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.

Survive the second turret standoff in Nova Prospekt.

Kill an enemy with a toilet.

Use the antlions to kill 50 enemies.

Cross the antlion beach in chapter Sandtraps without touching the sand.

Destroy six gunships in Half-Life 2.

Pin a soldier to the billboard in chapter Highway 17.

Kill 3 enemies using the crane.

Play through Ravenholm using only the Gravity Gun.

Use DOG's ball to make a basket in Eli's scrapyard.

Get the Gravity Gun in Black Mesa East.

Find the HEV Suit Charger faceplate in Eli's scrapyard.

Destroy the hunter-chopper in Half-Life 2.

Discover the hidden singing vortigaunt cave in chapter Water Hazard.

Get the airboat's mounted gun.

Get the airboat.

Kill five barnacles with one barrel.

Get the crowbar.

Break the mini-teleporter in Kleiner's lab.

Escape the apartment block raid.

Use flares to light 15 zombies on fire.

Steal a Zombie's grenade.

Kill an Elite Soldier with his own energy ball.

Kill five enemies with the same energy ball.

Kill a Combine soldier with his own grenade.

Kill five enemies with a Manhack.

Kill an enemy by planting a hopper mine.

Kill 30 enemies with thrown physics objects.