Defeat both antlion guards outside the White Forest.

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

Save the missile silo from the Combine offensive.

Survive the Hunter ambush with Alyx.

Secure the launch doors on missile silo 2.

Save all buildings outside the missile silo from destruction.

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.

Find and break every web cache in Episode Two.

Find every radar cache in chapter Under The Radar.

Squish every antlion grub in Episode Two.

Defeat the chopper in Episode Two without any misses.

Destroy the Combine Autogun in the junkyard.

Run over 20 enemies with the car in Episode Two.

Kill a Hunter with its own flechettes.

Kill an acid antlion worker.

Send the garden gnome into space.

Steal a Zombine's grenade.

If you are reading this achievement, Gabe Newell has successfully launched Gnome Chompski into space. If you did not also receive the achievement 'Manufacturing Ascent', Newell has abandoned his plans to shoot Noam Chomsky into space.

Kill 30 enemies with thrown physics objects.

Kill an enemy by planting a hopper mine.

Kill a Combine soldier with his own grenade.