Here is the full list of all 33 Half-Life 2: Update achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Hit the trashcan cop with the can.
Pin a soldier to the billboard in the chapter Highway 17.
Discover the hidden singing vortigaunt cave in chapter Water Hazard.
Play through Ravenholm using only the Gravity Gun.
Break the mini-teleporter in Kleiner's Lab.
Destroy the Citadel's reactore core.
Kill five enemies with a Manhack.
Disintegrate 15 soldiers by throwing them into a Combine ball field.
Survive the rooftop strider battle in the ruins of City 17.
Find all lambda caches in Half-Life 2.
Shut down the supression device by disabling its generators.
Kill all of the snipers in City 17.
Kill an enemy with a toilet.
Survive the generator plaza standoff in chapter Anticitizen One.
Get through the toxic tunnel under City 17 in Half-Life 2.
Gain command of a squad of rebels in the uprising.
Survive the second turret standoff in Nova Prospekt.
Use the Antlions to kill 50 enemies.
Destroy six gunships in Half-Life 2.
Cross the antlion beach in chapter Sandtraps without touching the sand.
Kill 3 enemies using the crane.
Defend Little Odessa from the Gunship attack.
Escort Gregori safely through the church cemetery.
Use Dog's ball to make a basket in the scrapyard.
Find the HEV Suit Charger faceplate in Eli's scrapyard.
Get the Gravity Gun in Black Mesa East.
Destroy the Hunter-Chopper.
Get the airboat's mounted gun.
Get the airboat.
Kill five barnacles with one explosive barrel.
Get the crowbar.
Escape the apartment block raid.
Put the can in the trash.