Kill 5 Enemies with one Grenade.
Use an entire clip of Gluon ammo in one continuous shot.
Kill an Assassin with the .357 Magnum.
Kill 10 airborne Headcrabs using the Shotgun.
Conduct all of the questionable research experiments.
Pass the toilet paper to the Scientist in need.
Ruin the microwave casserole.
Kill a Headcrab using fire.
Kill a Barnacle with a Satchel.
Refuse to insert the specimen into the Anti-Mass Spectrometer.
Get killed by your own Snarks.
Overcharge it anyway.
Get overtaken by a Headcrab's ample anterior.
Headshot 20 Enemies with the .357 Magnum.
Perform surgical caffeine extraction from 20 vending machines.
Use the alternate path in Office Complex.
Kill 20 Enemies with the Hivehand.
Kill 10 enemies with a reprogrammed Sentry.
Kill 10 Enemies with Snarks.
Drown in Lambda Core's coolant.
Kill a Marine with their own Grenade.
Kill an Ichthyosaur with either the Tau or Gluon.
Interfere with the alarm and laptop in Anomalous Materials.
Send the Hidden Hat to Xen.
Help the Barnacle and Headcrab find true love.
Kill all Protozoans in the Borderworld.
Don't kill any Vortigaunts in the Borderworld.
Kill 10 Enemies with Tripmines.
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.
Skip the opening Xen island with a secret jump.
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.
Complete Interloper without taking any laser damage.
Escape the Gargantua’s Lair without taking any damage from Gargantuas.
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.
Defeat Nihilanth in under 4 minutes.
Accept G-Man’s offer of employment.
Decline G-Man’s offer of employment.
Cook a Grenade for too long.
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