Here is the full list of all 50 Black Mesa achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Complete Interloper without taking any laser damage.
Kill all Protozoans in the Borderworld.
Escape the Gargantua’s Lair without taking any damage from Gargantuas.
Don't use the Cyanogen and let the Gonarch live.
Find each member of the missing research teams.
Use Cyanogen to kill Gonarch.
View the *other* secret ending.
Defeat Nihilanth in under 4 minutes.
Find the snack supply canister.
Carry the Hidden Hat to Endgame.
Take out all three Healing Crystals in Nihilanth’s Chamber at the same time.
Don't kill any Vortigaunts in the Borderworld.
Kill a Controller without killing any of its mind-controlled Vortigaunt slaves.
Deliver the finishing blow to Gonarch with your Crowbar.
Get whacked into oblivion in the ledge fight.
Assemble all the possible Scientists and Guards at the end of Office Complex.
Decline G-Man’s offer of employment.
Accept G-Man’s offer of employment.
Skip the opening Xen island with a secret jump.
Use the welcome mat.
Wait too long to jump into the Lambda Teleporter.
Escape the Hangar in Surface Tension without alerting the Soldiers.
Kill 10 Enemies with Tripmines.
Cook a Grenade for too long.
Die in the AMS Beam before starting the experiment.
Send the Hidden Hat to Xen.
Drown in Lambda Core's coolant.
Use an entire clip of Gluon ammo in one continuous shot.
Kill 20 enemies with the Hivehand.
Kill an Icthyosaur with either the Tau or Gluon.
Conduct all of the questionable research experiments.
Overcharge it anyway.
Kill a Headcrab using fire.
Kill 10 enemies with Snarks.
Get killed by your own Snarks.
Kill an Assassin with the .357 Magnum.
Kill 10 enemies with a reprogrammed Sentry.
Kill a Barnacle with a Satchel.
Kill 10 Airborne Headcrabs using the Shotgun.
Headshot 20 enemies with the .357 magnum.
Kill a Marine with their own grenade.
Kill 5 enemies with one grenade.
Use the alternate path in Office Complex.
Help the Barnacle and Headcrab find true love.
Get overtaken by a Headcrab's ample anterior.
Perform surgical caffeine extraction from 20 machines.
Refuse to insert the specimen into the Anti-Mass Spectrometer.
Pass the toilet paper to the scientist in need.
Ruin the microwave casserole.
Interfere with the alarm and laptop in Anomalous Materials.