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Secret Achievements (Show)
Black Mesa Achievements
Pass the toilet paper to the Scientist in need.
Perform surgical caffeine extraction from 20 vending machines.
Kill 10 airborne Headcrabs using the Shotgun.
Kill 20 Enemies with the Hivehand.
Ruin the microwave casserole.
Kill an Assassin with the .357 Magnum.
Kill 10 enemies with a reprogrammed Sentry.
Conduct all of the questionable research experiments.
Kill 10 Enemies with Snarks.
Gray Matter Propulsion
Headshot 20 Enemies with the .357 Magnum.
Hyper Saturation Conundrum
Drown in Lambda Core's coolant.
Kill a Headcrab using fire.
Kill a Marine with their own Grenade.
Kill 5 Enemies with one Grenade.
Kill an Ichthyosaur with either the Tau or Gluon.
Use the alternate path in Office Complex.
Use an entire clip of Gluon ammo in one continuous shot.
Get overtaken by a Headcrab's ample anterior.
Interfere with the alarm and laptop in Anomalous Materials.
Overcharge it anyway.
Send the Hidden Hat to Xen.
Kill a Barnacle with a Satchel.
Refuse to insert the specimen into the Anti-Mass Spectrometer.
Unified Coupling Theorum
Help the Barnacle and Headcrab find true love.
Get killed by your own Snarks.
Kill all Protozoans in the Borderworld.
PhD in Pacifism
Don't kill any Vortigaunts in the Borderworld.
The Rarest Specimen
Carry the Hidden Hat to Endgame.
One Step Ahead
Kill 10 Enemies with Tripmines.
Escape the Hangar in Surface Tension without alerting the Soldiers.
Wait too long to jump into the Lambda Teleporter.
Our Brains And Your Brawn
Assemble all the possible Scientists and Guards at the end of Office Complex.
Less Than Desirable Consequences
Die in the AMS Beam before starting the experiment.
Skip the opening Xen island with a secret jump.
Following the Rules
Use the welcome mat.
Deliver the finishing blow to Gonarch with your Crowbar.
Get whacked into oblivion in the ledge fight.
Find each member of the missing research teams.
Use Cyanogen to kill Gonarch.
Don't use the Cyanogen and let the Gonarch live.
Find the snack supply canister.
Complete Interloper without taking any laser damage.
Black Mesa Decathlon Winner
Escape the Gargantua’s Lair without taking any damage from Gargantuas.
Anti-Matter Over Mind
Kill a Controller without killing any of its mind-controlled Vortigaunt slaves.
Take out all three Healing Crystals in Nihilanth’s Chamber at the same time.
Late for Work
Defeat Nihilanth in under 4 minutes.
Accept G-Man’s offer of employment.
Rather an Anticlimax
Decline G-Man’s offer of employment.
View the *other* secret ending.
Cook a Grenade for too long.