Kill an acid antlion worker.

Steal a zombine's grenade.

Squish every antlion grub in Episode Two.

Find and break every web cache in Episode Two.

Defeat both antlion guards outside the White Forest.

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

Run over 20 enemies with the car in Episode Two.

Survive the Hunter ambush with Alyx.

Destroy the Combine Autogun in the junkyard.

Defeat the chopper in Episode Two without any misses.

Find every radar cache in chapter Under The Radar.

Beat DOG in a race to the White Forest base.

Survive the ambush at White Forest Inn.

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

Send the garden gnome into space.

Secure the launch doors on missile silo 2.

Save the missile silo from the Combine offensive.

Save all buildings outside the missile silo from destruction.

Kill a Hunter with its own flechettes.

Kill 30 enemies with thrown physics objects.

Kill a Combine soldier with his own grenade.

Kill an enemy by planting a hopper mine.