Universal Gravitation
Not unlocked yetGet killed by your own Snarks.
Prolific Popper
Not unlocked yetKill all Protozoans in the Borderworld.
PhD in Pacifism
Not unlocked yetDon't kill any Vortigaunts in the Borderworld.
The Rarest Specimen
Not unlocked yetCarry the Hidden Hat to Endgame.
One Step Ahead
Not unlocked yetKill 10 Enemies with Tripmines.
Stealth Technology
Not unlocked yetEscape the Hangar in Surface Tension without alerting the Soldiers.
xen when
Not unlocked yetWait too long to jump into the Lambda Teleporter.
Our Brains And Your Brawn
Not unlocked yetAssemble all the possible Scientists and Guards at the end of Office Complex.
Less Than Desirable Consequences
Not unlocked yetDie in the AMS Beam before starting the experiment.
Orbital Trajectory
Not unlocked yetSkip the opening Xen island with a secret jump.
Following the Rules
Not unlocked yetUse the welcome mat.
Doctor’s Signature
Not unlocked yetDeliver the finishing blow to Gonarch with your Crowbar.
Gonad Glider
Not unlocked yetGet whacked into oblivion in the ledge fight.
Post-Mortem Interval
Not unlocked yetFind each member of the missing research teams.
The Plan
Not unlocked yetUse Cyanogen to kill Gonarch.
Unquestionably Ethical
Not unlocked yetDon't use the Cyanogen and let the Gonarch live.
Contest Propellant
Not unlocked yetFind the snack supply canister.
Laser Immunization
Not unlocked yetComplete Interloper without taking any laser damage.
Black Mesa Decathlon Winner
Not unlocked yetEscape the Gargantua’s Lair without taking any damage from Gargantuas.
Anti-Matter Over Mind
Not unlocked yetKill a Controller without killing any of its mind-controlled Vortigaunt slaves.
Specimen GG
Not unlocked yetTake out all three Healing Crystals in Nihilanth’s Chamber at the same time.
Late for Work
Not unlocked yetDefeat Nihilanth in under 4 minutes.
Limitless Potential
Not unlocked yetAccept G-Man’s offer of employment.
Rather an Anticlimax
Not unlocked yetDecline G-Man’s offer of employment.