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| "Radiation Levels Detected" (5) | Get through the toxic tunnel under City 17 in Half-Life 2. |
| Acid Reflex (5) | Kill an acid antlion worker. |
| Anchor's Aweigh! (5) | Get the airboat. |
| Aperture Science (40) | Earn gold medals on all Portal challenges. |
| Atomizer (10) | Disintegrate 15 soldiers by throwing them into a Combine ball field. |
| Attica! (5) | Destroy the gunship in the hospital attic. |
| Barnacle Bowling (5) | Kill five barnacles with one barrel. |
| Basic Science (10) | Earn bronze medals on all Portal challenges. |
| Blast from the Past (10) | Find the HEV Suit Charger faceplate in Eli's scrapyard. |
| Bone Breaker (5) | Kill 30 enemies with thrown physics objects. |
| Bug Hunt (10) | Use the antlions to kill 50 enemies. |
| Cache Checker (10) | Find every radar cache in chapter Under The Radar. |
| Camera Shy (5) | Detach security cameras from the walls. |
| Car Crusher (5) | Use the cars to squash 15 antlions in Episode One. |
| Citizen Escort (15) | Don't let any citizens die when escorting them to the escape train. |
| Conservationist (5) | Kill five enemies with the same energy ball. |
| Containment (5) | Contain the Citadel core. |
| Counter-Sniper (5) | Kill all of the snipers in City 17. |
| Cupcake (10) | Beat two Portal advanced maps. |
| Deadly Harvest (5) | Kill an enemy by planting a hopper mine. |
| Defiance (5) | Throw the trash at the guard in the beginning of HL:2 |
| Dynasty (10) | Win 20 games. |
| Elevator Action (10) | Survive long enough to get on the parking garage elevator. |
| Escape From City 17 (20) | Escape City 17 with Alyx. |
| Fight the Power (10) | Shut down the supression device by disabling its generators. |
| Flamethrower (5) | Set five enemies on fire in 30 seconds. |
| Flushed (5) | Kill an enemy with a toilet. |
| Follow Freeman (10) | Gain command of a squad of rebels in the uprising. |
| Fratricide (5) | Do whatever it takes to survive. |
| Friendly Fire (5) | Knock down a turret with another turret. |
| Fruitcake (20) | Beat four Portal advanced maps. |
| Get Some Grub (20) | Squish every antlion grub in Episode Two. |
| Giant Killer (10) | Survive the rooftop strider battle in the ruins of City 17. |
| Gordon Propelled Rocket (5) | Unlock the rocket launcher lambda cache in chapter Under The Radar. |
| Grave Robber (5) | Steal a Zombine's grenade. |
| Grey Matter (5) | Get 25 headshots as a Sniper. |
| Hack Attack! (5) | Kill five enemies with a Manhack. |
| Hard to Kill (10) | Get five kills in a row without dying. |
| Hardcore (15) | Accumulate 1000 total kills. |
| Head of the Class (5) | Play a complete round with every class. |
| Heartbreaker (10) | Complete Portal. |
| Heavy Weapons (5) | Get the airboat's mounted gun. |
| Hit and Run (5) | Run over 20 enemies with the car in Episode Two. |
| Hot PotatOwned (10) | Kill a Combine soldier with his own grenade. |
| Impenetrable Defense (10) | Successfully defend Dustbowl without giving up a capture. |
| Impossible Defense (30) | Successfully defend Gravel Pit without giving up a capture. |
| Into the Breach (5) | Help Griggs and Sheckley hold off the antlion invasion inside the mine shaft. |
| Keep Off the Sand! (20) | Cross the antlion beach in chapter Sandtraps without touching the sand. |
| Lab Rat (5) | Acquire the fully powered Aperture Science Handheld Portal Device. |
| Lambda Locator (15) | Find all lambda caches in Half-Life 2. |
| Lightning Offense (10) | Win Well in 5 minutes or less. |
| Little Rocket Man (30) | Send the garden gnome into space. |
| Live Bait (10) | Help Alyx snipe 30 enemies in Episode One. |
| Long Jump (5) | Jump 300 feet. |
| Malcontent (5) | Escape the apartment block raid. |
| Master of Disguise (15) | Trick an opposing medic into healing you. |
| Neighborhood Watch (35) | Save all buildings outside the missile silo from destruction. |
| Nemesis (5) | Get five revenge kills. |
| One Man Army (5) | Destroy six gunships in Half-Life 2. |
| OSHA Violation (5) | Kill 3 enemies using the crane. |
| Pacifist (10) | Contain the Citadel core without killing any stalkers. |
| Partygoer (5) | Make the correct party escort submission position decision. |
| Payback (10) | Kill a Hunter with its own flechettes. |
| Pedal to the Metal (5) | Beat DOG in a race to the White Forest base. |
| Pinata Party (5) | Find and break every web cache in Episode Two. |
| Plaza Defender (10) | Survive the generator plaza standoff in chapter Anticitizen One. |
| Powerhouse Offense (5) | Win 2Fort with a shutout. |
| Puttin' On a Clinic (15) | Defeat the chopper in Episode Two without any misses. |
| Relentless Offense (20) | Win Hydro without giving up a capture. |
| Revenge! (10) | Destroy the hunter-chopper in Half-Life 2. |
| Rocket Science (20) | Earn silver medals on all Portal challenges. |
| Targetted Advertising (5) | Pin a soldier to the billboard in chapter Highway 17. |
| Team Doctor (5) | Accumulate 25000 heal points as a Medic. |
| Terminal Velocity (5) | Fall 30,000 feet. |
| The One Free Bullet (40) | Beat Episode One firing exactly one bullet. Grenade, crowbar, rocket, and Gravgun kills are okay! |
| Think Fast! (10) | Kill an Elite Soldier with his own energy ball. |
| Trusty Hardware (5) | Get the crowbar. |
| Turret (5) | Accumulate 10 turret kills with a single turret. |
| Two Points (2) | Use DOG's ball to make a basket in Eli's scrapyard. |
| Vanilla Crazy Cake (30) | Beat all six Portal advanced maps. |
| Vorticough (13) | Discover the hidden singing vortigaunt cave in chapter Water Hazard. |
| Warden Freeman (10) | Survive the second turret standoff in Nova Prospekt. |
| Watch Your Head! (5) | Make it to the bottom of the Citadel's main elevator shaft in one piece. |
| What cat? (5) | Break the mini-teleporter in Kleiner's lab. |
| With Friends Like these... (10) | Play in a game with seven or more players from your friends list. |
| World Traveler (5) | Play a complete game on every map. |
| Zero-Point Energy (5) | Get the Gravity Gun in Black Mesa East. |
| Zombie Chopper (25) | Play through Ravenholm using only the Gravity Gun. |
| Zombie-que (5) | Use flares to light 15 zombies on fire. |
