Half-Life 2 achievements

Save all buildings outside the missile silo from destruction.

Squish every antlion grub in Episode Two.

Find and break every web cache in Episode Two.

Kill a Combine soldier with his own grenade.

Defeat the chopper in Episode Two without any misses.

Kill a Hunter with its own flechettes.

Send the garden gnome into space.

Kill five enemies with the same energy ball.

Finish the game firing exactly one bullet. Grenade, crowbar, rocket, and Gravity Gun kills are okay!

Use flares to light 15 zombies on fire.

Contain the Citadel core without killing any stalkers.

Kill 30 enemies with thrown physics objects.