Cobiah

Disintegrate 15 soldiers by throwing them into a Combine ball field.

Survive the rooftop strider battle in the ruins of City 17.

Survive the second turret standoff in Nova Prospekt.

Pin a soldier to the billboard in chapter Highway 17.

Destroy six gunships in Half-Life 2.

Shut down the supression device by disabling its generators.

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.

Use the antlions to kill 50 enemies.

Use DOG's ball to make a basket in Eli's scrapyard.

Get the Gravity Gun in Black Mesa East.

Find the HEV Suit Charger faceplate in Eli's scrapyard.

Destroy the hunter-chopper in Half-Life 2.

Get the airboat's mounted gun.

Get the airboat.

Kill five barnacles with one barrel.

Get the crowbar.

Escape the apartment block raid.

Break the mini-teleporter in Kleiner's lab.

Discover the hidden singing vortigaunt cave in chapter Water Hazard.

Play through Ravenholm using only the Gravity Gun.

Kill 3 enemies using the crane.

Cross the antlion beach in chapter Sandtraps without touching the sand.

Kill an enemy with a toilet.

Kill all of the snipers in City 17.

Find all lambda caches in Half-Life 2.

Kill five enemies with a Manhack.