What cat?

Break the mini-teleporter in Kleiner's lab.

Defiant

Hit the trashcan cop with the can.

Fight the Power

Shut down the supression device by disabling its generators.

Plaza Defender

Survive the generator plaza standoff in chapter Anticitizen One.

"Radiation Levels Detected"

Get through the toxic tunnel under City 17 in Half-Life 2.

Follow Freeman

Gain command of a squad of rebels in the uprising.

Warden Freeman

Survive the second turret standoff in Nova Prospekt.

Partygoer

Make the correct party escort submission position decision.

Fratricide

Do whatever it takes to survive.

Friendly Fire

Knock down a turret with another turret.

One Man Army

Destroy six gunships in Half-Life 2.

Bug Hunt

Use the antlions to kill 50 enemies.

Where Cubbage Fears to Tread

Defend Little Odessa from the gunship attack.

Hallowed Ground

Escort Gregori safely through the church cemetery.

Bone Breaker

Kill 30 enemies with thrown physics objects.

Zero-Point Energy

Get the Gravity Gun in Black Mesa East.

Revenge!

Destroy the hunter-chopper in Half-Life 2.

Heavy Weapons

Get the airboat's mounted gun.

Anchor's Aweigh!

Get the airboat.

Trusty Hardware

Get the crowbar.

Malcontent

Escape the apartment block raid.

Into the Breach

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

Deadly Harvest

Kill an enemy by planting a hopper mine.

Acid Reflex

Kill an acid antlion worker.

Elevator Action

Survive long enough to get on the parking garage elevator.

Containment

Contain the Citadel core.

Watch Your Head!

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

Lab Rat

Acquire the fully powered Aperture Science Handheld Portal Device.

Heartbreaker

Complete Portal.

Live Bait

Help Alyx snipe 30 enemies in Episode One.