Achievement Breakdown:
Story Related: (2)
Missable: (13)
Secondary Objectives: (13)
Collectibles: (2)
Slay: (13)
Miscellaneous: (7)


1. Limitless Potential: Accept G-Man’s offer of employment.


2. Rather An Anticlimax: Decline G-Man’s offer of employment.


1. Ethically Questionable: Conduct all 5 of the questionable research experiments.


2. Stealth Technology: Escape the Hangar in Surface Tension without alerting the Soldiers.


3. The Plan: Use Cyanogen to kill Gonarch.


4. Unquestionably Ethical: Don't use the Cyanogen & let the Gonarch live.


5. Doctor’s Signature: Deliver the finishing blow to Gonarch with your Crowbar.


6. Black Mesa Decathlon Winner: Escape the Gargantua’s Lair without taking any damage from Gargantuas.


7. PhD In Pacifism: Don't kill any Vortigaunts in the Borderworld.


8. Laser Immunization: Complete Interloper without taking any laser damage.


9. Late For Work: Defeat Nihilanth in under 4 minutes.


10. Specimen GG: Take out all three Healing Crystals in Nihilanth’s Chamber at the same time.


11. Rare Specimen: Send the Hidden Hat to Xen.


12. The Rarest Specimen: Carry the Hidden Hat to Endgame.


13. Pepperoni Precipitation: View the *other* Secret Ending.


1. Proverbial Tinkerer: Interfere with the alarm & laptop in Anomalous Materials.


2. Convection Refinement: Ruin the microwave casserole.


3. Caffeine Extraction: Perform surgical caffeine extraction from 20 machines.


4. Brownian Motion: Pass the toilet paper to the Scientist in need.


5. Less Than Desirable Consequences: Die in the AMS beam before starting the experiment.


6. Resonance Procrastinator: Refuse to insert the specimen into the Anti-Mass Spectrometer.


7. Permeable Infrastructure: Use the alternate path in Office Complex.


8. Our Brains & Your Brawn: Assemble all 6 of the possible Scientists & Guards at the end of Office Complex.


9. Xen When: Wait too long to jump into the Lambda Teleporter.


10. Orbital Trajectory: Skip the opening Xen island with a secret jump.


11. Following the Rules: Use the welcome mat.


12. Gonad Glider: Get whacked into oblivion in the ledge fight.


13. Contest Propellant: Find the snack supply canister.


1. Post-Mortem Interval: Find each member of the 7 missing Research Teams.


2. Prolific Popper: Kill all 64 Protozoans in the Borderworld.


1. Inflammatory Actions: Kill a Headcrab using fire.


2. Mega Hertz: Kill 5 enemies with one Grenade.


3. Digital Wizardry: Kill 10 enemies with a reprogrammed Sentry.


4. Kinetic Repulsion: Kill a Marine with their own Grenade.


5. Calculated Trajectory: Kill 10 Airborne Headcrabs using the Shotgun.


6. Remote Detonation: Kill a Barnacle with a Satchel.


7. One Step Ahead: Kill 10 enemies with Trip Mines.


8. Grey Matter Propulsion: Headshot 20 enemies with the .357 Magnum.


9. Dead Reckoning: Kill an Assassin with the .357 Magnum.


10. Futile Resistance: Kill 10 enemies with Snarks.


11. Centripetal Attraction: Kill 20 enemies with the Hivehand.


12. Nuclear Fishin’: Kill an Icthyosaur with either the Tau or Gluon.


13. Anti-Matter Over Mind: Kill a Controller without killing any of its mind-controlled Vortigaunt slaves.


1. Prophylactic Suggested: Get overtaken by a Headcrab's ample anterior.


2. Well-Done: Cook a Grenade for too long.


3. Unified Coupling Theorem: Help the Barnacle & Headcrab find true love.


4. Universal Gravitation: Get killed by your own Snarks.


5. Quantum Capacitance: Overcharge it anyway.


6. Premature Expulsion: Use an entire clip of Gluon ammo in one continuous shot.


7. Hyper Saturation Conundrum: Drown in Lambda Core's coolant.