Acid Reflex
Not unlocked yetKill an acid antlion worker.
Get Some Grub
Not unlocked yetSquish every antlion grub in Episode Two.
Piñata Party
Not unlocked yetFind and break every web cache in Episode Two.
Into the Breach
Not unlocked yetHelp Griggs and Sheckley hold off the antlion invasion inside the mine shaft.
Twofer
Not unlocked yetDefeat both antlion guards outside the White Forest.
Hit and Run
Not unlocked yetRun over 20 enemies with the car in Episode Two.
Meet the Hunters
Not unlocked yetSurvive the Hunter ambush with Alyx.
Puttin' On a Clinic
Not unlocked yetDefeat the chopper in Episode Two without any misses.
Gunishment!
Not unlocked yetDestroy the Combine Autogun in the junkyard.
Cache Checker
Not unlocked yetFind every radar cache in chapter Under The Radar.
Pedal to the Metal
Not unlocked yetBeat DOG in a race to the White Forest base.
Gordon Propelled Rocket
Not unlocked yetUnlock the rocket launcher lambda cache in chapter Under The Radar.
Quiet Mountain Getaway
Not unlocked yetSurvive the ambush at White Forest Inn.
Little Rocket Man
Not unlocked yetSend the garden gnome into space.
Secondary Silo Secured
Not unlocked yetSecure the launch doors on missile silo 2.
Neighborhood Watch
Not unlocked yetSave all buildings outside the missile silo from destruction.
Defense of the Armament
Not unlocked yetSave the missile silo from the Combine offensive.
Payback
Not unlocked yetKill a Hunter with its own flechettes.
Bone Breaker
Not unlocked yetKill 30 enemies with thrown physics objects.
Deadly Harvest
Not unlocked yetKill an enemy by planting a hopper mine.
Hot Potat0wned
Not unlocked yetKill a Combine soldier with his own grenade.
Grave Robber
Not unlocked yetSteal a Zombine's grenade.
Gnome Alone
Not unlocked yetIf 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.