Watch Your Head!
Objective: Make it to the bottom of the Citadel's main elevator shaft in one piece.
Objective: Contain the Citadel core.
Objective: Survive long enough to get on the parking garage elevator.
Objective: Destroy the gunship in the hospital attic.
Escape From City 17
Objective: Escape City 17 with Alyx.
Objective: Help Alyx snipe 30 enemies in Episode One.
Objective: Don't let any citizens die when escorting them to the escape train.
Objective: Kill an Elite Soldier with his own energy ball.
Objective: Use the cars to squash 15 antlions in Episode One.
Objective: Contain the Citadel core without killing any stalkers.
Objective: Kill five enemies with the same energy ball.
The One Free Bullet
Objective: Finish the game firing exactly one bullet. Grenade, crowbar, rocket, and Gravity Gun kills are okay!
Objective: Use flares to light 15 zombies on fire.