Escape the apartment block raid.
Break the mini-teleporter in Kleiner's lab.
Get the crowbar.
Get the Airboat.
Get the Airboat's mounted gun.
Discover the hidden singing vortigaunt cave in Water Hazard.
Destroy the Hunter-Chopper.
Find the HEV Suit Charger faceplate in Eli's scrapyard.
Get the Gravity Gun in Black Mesa East.
Make a basket in Eli's scrapyard.
Beat Ravenholm using only the Gravgun.
Kill 3 enemies using the crane.
Pin the soldier to the billboard with the Crossbow in Highway 17.
Cross the antlion beach in Sandtraps without touching the sand.
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.
Survive the Generator Plaza standoff in Anticitizen One.
Kill all of the snipers in Follow Freeman.
Shut down the supression device by disabling its generators.
Survive the rooftop Strider battle in the ruins of City 17.
Find all of the lambda caches.
Kill five barnacles with one explosive barrel.
Kill an enemy with a toilet.
Destroy six Gunships
Use the Antlions to kill 50 enemies.
Kill five enemies with Manhacks.
Disintegrate 15 soldiers by throwing them into a Combine ball field.