Here is the full list of all 33 Half-Life 2 achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Pin a soldier to the billboard in chapter Highway 17.
Kill 3 enemies using the crane.
Discover the hidden singing vortigaunt cave in chapter Water Hazard.
Kill all of the snipers in City 17.
Use DOG's ball to make a basket in Eli's scrapyard.
Disintegrate 15 soldiers by throwing them into a Combine ball field.
Survive the rooftop strider battle in the ruins of City 17.
Use the antlions to kill 50 enemies.
Destroy the hunter-chopper in Half-Life 2.
Get the airboat.
Escape the apartment block raid.
Break the mini-teleporter in Kleiner's lab.
Get the crowbar.
Kill five barnacles with one barrel.
Get the airboat's mounted gun.
Find the HEV Suit Charger faceplate in Eli's scrapyard.
Get the Gravity Gun in Black Mesa East.
Play through Ravenholm using only the Gravity Gun.
Destroy six gunships in Half-Life 2.
Cross the antlion beach in chapter Sandtraps without touching the sand.
Kill an enemy with a toilet.
Survive the second turret standoff in Nova Prospekt.
Gain command of a squad of rebels in the uprising.
Get through the toxic tunnel under City 17 in Half-Life 2.
Survive the generator plaza standoff in chapter Anticitizen One.
Shut down the supression device by disabling its generators.
Find all lambda caches in Half-Life 2.
Kill five enemies with a Manhack.