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