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