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