Score 60,000 points in a Short Game.
Score 25,000 points in a Short Game.
Score 40,000 points in a Short Game.
Successfully answer every Sequentials or Credit Roll question in one puzzle block.
Got through a Gather with no damage and no one getting to the Little Sister.
Adopted a new Little Sister for the first time.
Hacked one of each kind of machine.
Upgraded a weapon at a Power to the People Station.
Defended yourself against Lamb's assault in the train station.
Used the Hack Tool to hack an object at a distance.
Found your way back into the ruins of Rapture.
Joined forces with Sinclair in Ryan Amusements.
Confronted Lamb's lieutenant in Pauper's Drop.
Defeated the Preacher.
Bought one Plasmid or Tonic Slot at a Gatherer's Garden.
Installed the third upgrade to a weapon.
Researched a Splicer with the Research Camera.
Defended yourself against the Big Sister without dying.
Killed 30 enemies using only Traps.
Killed an enemy with its own projectile.
Spent 2000 dollars at Vending Machines.
Successfully call UNO! and win the game.
Change the color of the discard pile 5 or more times in a single round.
Altered Beast: Collect 100,000 pts or higher by the end of the first level
Ristar: Collect 5 Yellow Stars
Shinobi III: Complete first level without using continues
Super Thunder Blade: Score over 1,500,000 points in the first level
Escape City 17 with Alyx.
Don't let any citizens die when escorting them to the escape train.
Destroy the gunship in the hospital attic.
Help Alyx snipe 30 enemies in Episode One.
Survive long enough to get on the parking garage elevator.
Steal a Zombine's grenade.
Contain the Citadel core.
Make it to the bottom of the Citadel's main elevator shaft in one piece.
Continue playing to unlock this secret achievement.
Kill five enemies with the same energy ball.
Survive the rooftop strider battle in the ruins of City 17.
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.
Kill an enemy by planting a hopper mine.
Gain command of a squad of rebels in the uprising.
Survive the second turret standoff in Nova Prospekt.
Destroy six gunships in Half-Life 2.
Use the antlions to kill 50 enemies.
Pin a soldier to the billboard in chapter Highway 17.
Kill 3 enemies using the crane.