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