Atomizer
Disintegrate 15 soldiers by throwing them into a Combine ball field.
Hack Attack!
Kill five enemies with a Manhack.
Targetted Advertising
Pin a soldier to the billboard in chapter Highway 17.
Zombie Chopper
Play through Ravenholm using only the Gravity Gun.
Flushed
Kill an enemy with a toilet.
Two Points
Use DOG's ball to make a basket in Eli's scrapyard.
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.
What cat?
Break the mini-teleporter in Kleiner's lab.
Watch Your Head!
Make it to the bottom of the Citadel's main elevator shaft in one piece.
Containment
Contain the Citadel core.
Elevator Action
Survive long enough to get on the parking garage elevator.
Attica!
Destroy the gunship in the hospital attic.
Citizen Escort
Don't let any citizens die when escorting them to the escape train.
Escape From City 17
Escape City 17 with Alyx.
Conservationist
Kill five enemies with the same energy ball.
Think Fast!
Kill an Elite Soldier with his own energy ball.
Acid Reflex
Kill an acid antlion worker.
Into the Breach
Help Griggs and Sheckley hold off the antlion invasion inside the mine shaft.
Twofer
Defeat both antlion guards outside the White Forest.