Kill an enemy by planting a hopper mine.

Kill an acid antlion worker.

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

Defeat both antlion guards outside the White Forest.

Run over 20 enemies with the car in Episode Two.

Survive the Hunter ambush with Alyx.

Destroy the Combine Autogun in the junkyard.

Find every radar cache in chapter Under The Radar.

Beat DOG in a race to the White Forest base.

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

Survive the ambush at White Forest Inn.

Secure the launch doors on missile silo 2.

Save the missile silo from the Combine offensive.

Steal a Zombine's grenade.