my personal black mesa video game achievement tracking list

Jump to tips on the hat/pizza achievements

Black Mesa Inbound > Anomalous Materials > Unforeseen Consequences > Office Complex > "We've Got Hostiles" > Blast Pit > Power Up > On A Rail > Apprehension > Residue Processing > Questionable Ethics > Surface Tension > "Forget About Freeman!" > Lambda Core > Xen > Gonarch's Lair > Interloper > Nihilanth > End Game > Credits.

Pepperoni PrecipitationQuestionable Ethics → EndgameView the *other* secret ending.carry the pizza from Ques­tio­nable Ethics cafeteria to the Nihilanth
Rare SpecimenUnforeseen Consequences → Lambda CoreSend the Hidden Hat to Xen.near entrance to Sector C
The Rarest SpecimenUnforeseen Consequences → EndgameCarry the Hidden Hat to Endgame.all the way to the Nihilanth
Futile ResistanceQuestionable Ethics →Kill 10 enemies with Snarks.
Ethically QuestionableQuestionable EthicsConduct all of the ques­tio­nable research experiments.kill alien grunt (in the green liquid chamber), bullsquid (with tesla discharge), snarks (fire them until it breaks), head­crabs (use cyanogen gas against the ones in the Xen terrarium, and also shoot them with the super­laser in the tau cannon area)
Universal GravitationQuestionable Ethics →Get killed by your own Snarks.
One Step AheadPower Up →Kill 10 Enemies with Tripmines.
Unified Coupling TheorumUnforeseen Consequences →Help the Barnacle and Headcrab find true love.supposedly easiest on the conveyor belt in We've Got Hostiles, but the tree map part of Xen was easiest for me
Kinetic RepulsionWe've Got Hostiles →Kill a Marine with their own grenade.
Digital WizardryWe've Got Hostiles →Kill 10 enemies with a reprogrammed Sentry.
Well-DoneUnforeseen Consequences →Cook a grenade for too long.right-click (alt fire), hold it
Our Brains And Your BrawnOffice ComplexAssemble all the possible Scientists and Guards at the end of Office Complex.gather four guards (including the one near the start) and one male and one female scientist to the ele­vator shaft at the end
Prophylactic SuggestedUnforeseen Consequences →Get overtaken by a Headcrab's ample anterior.just let a head­crab kill you
Anti-Matter Over MindInterloperKill a Controller without killing any of its mind-controlled Vortigaunt slaves.
Black Mesa Decathlon WinnerInterloperEscape the Gargantua's Lair without taking any damage from Gargantuas.cannot take any damage from gargantuas in the whole map, cannot load saves in the map, have to load from the previous map
Brownian MotionAnomalous MaterialsPass the toilet paper to the scientist in need.
Caffeine ExtractionAnomalous Materials →Perform surgical caffeine extraction from 20 machines.cause damage to a vending machine and recover health from the soda cans
Calculated TrajectoryOffice Complex →Kill 10 Airborne Headcrabs using the Shotgun.
Centripetal AttractionSurface Tension →Kill 20 enemies with the Hivehand.
Contest PropellantInterloperFind the snack supply a room hidden behind wicker crates after the first battle against alien controllers in Interloper, right before an elevator
Convection RefinementAnomalous MaterialsRuin the microwave casserole.
Dead ReckoningApprehension, Lambda CoreKill an Assassin with the .357 Magnum.
Doctor's SignatureGonarch's LairDeliver the finishing blow to Gonarch with your Crowbar.
Following the RulesXenUse the welcome mat.start of tent laboratories on Xen: crouch on it or use the interact key
Gonad GliderGonarch's LairGet whacked into oblivion in the ledge fight.
Gray Matter PropulsionBlast Pit →Headshot 20 enemies with the .357 Magnum.
Hyper Saturation ConundrumLambda CoreDrown in Lambda Core's coolant.
Inflammatory ActionsUnforeseen Consequences →Kill a Headcrab using fire.use a flare, don't cause any other damage
Laser ImmunizationInterloperComplete Interloper without taking any laser lightning in the grunt factory counts as a laser, and green poison goo might count as one too
Late for WorkNihilanthDefeat Nihilanth in under 4 minutes.
Less Than Desirable ConsequencesAnomalous MaterialsDie in the AMS Beam before starting the experiment.
Limitless PotentialEndgameAccept G-Man's offer of employment.
Mega HertzUnforeseen Consequences →Kill 5 enemies with one grenade.easiest on some stacks of barnacles
Nuclear Fishin'Surface Tension →Kill an Ichthyosaur with either the Tau or Gluon.
Orbital TrajectoryXenSkip the opening Xen island with a secret jump.
Permeable InfrastructureOffice ComplexUse the alternate path in Office the rather open office area divided with dividers into cubicles (not separate rooms) with meeting rooms all around, where you battle vortigaunts; there's a meeting room with couches that has a short ladder drop down from the ceiling.
PhD in PacifismInterloperDon't kill any Vortigaunts in the Borderworld.includes vorts controlled by controllers
Post-Mortem IntervalGonarch's LairFind each member of the missing research use (E) on each of them, or crouch
Premature ExpulsionLambda Core →Use an entire clip of Gluon ammo in one continuous shot.
Prolific PopperXen → InterloperKill all Protozoans in the Borderworld.achi needs 64 killed. 37 in Xen, 22 in Gonarch's Lair (one requires the cyanogen canister), 8 at the end of Interloper, so 67 avail­able.
Proverbial TinkererAnomalous MaterialsInterfere with the alarm and laptop in Anomalous Materials.the alarm is under the circular reception desk right at the very start of the level
Quantum CapacitanceQuestionable Ethics →Overcharge it anyway.(The Tau Cannon.)
Rather an AnticlimaxEndgameDecline G-Man's offer of employment.
Remote DetonationBlast Pit →Kill a Barnacle with a Satchel.
Resonance ProcrastinatorAnomalous MaterialsRefuse to insert the specimen into the Anti-Mass Spectrometer.
Specimen GGNihilanthTake out all three Healing Crystals in Nihilanth's Chamber at the same time.using satchel charges
Stealth TechnologySurface TensionEscape the Hangar in Surface Tension without alerting the Soldiers.follow the dude, quicksave before trying
The PlanXen → Gonarch's LairUse Cyanogen to kill Gonarch.cyanogen picked up towards the end of the labora­tories on Xen; it's bright yellow and has a warning label on it reading "compressed cyanogen chloride"
Unquestionably EthicalXen → Gonarch's LairDon't use the Cyanogen and let the Gonarch live.the room with the cyanogen injector is high up and you can jump to a ledge and avoid the fight
xen whenLambda CoreWait too long to jump into the Lambda minute after it opens

rare/rarest specimen and pepperoni precipitation tips:

General notes for Pepperoni Precipitation: I'd say this is in general easier than The Rarest Specimen, for the main reason that the pizza is all flat edges while the hat rolls easily. It's not entirely easier, though: the pizza is much bigger than the hat, and for example many enclosed ladders are much harder, because you'll only fit in a certain angle or not fit at all, having to carry the pizza outside the ladder, or dropping it on your head and then crowbaring it above you. The pizza is also more difficult in Interloper's sucking air and water vents, because it'll easily get stuck and left behind, but this can happen with the hat also. With teleporters: like with carrying the hat, you'll need to walk into teleporters pizza-first, because otherwise it'll be left behind at the source. After teleportation the pizza will spawn at your feet (or rather, you'll spawn on top of it), and you'll be stuck for a moment: crowbar the pizza a bit and you'll be free.

I believe it's almost possible but actually impossible to do both the pizza achievement and hat achievement at once. Both items are very light for their size, and can't be thrown a long distance; the hat can be thrown further than the pizza, but a flare can be thrown further than the hat. There are two main reasons why I believe doing both at once is impossible: Gonarch's Lair (the gonarch is very powerful and will kill you if you stall by chucking both items along) and the air vents in Interloper. Maybe with speedrun-like strats its possible to do both while skipping most of the levels, but I'm doubtful.

On the other hand, it is possible to carry both the purple Hidden Hat and the cyanogen canister, which is used to skip the Gonarch boss fight. (It's also used for The Plan and Unquestionably Ethical, and required for part of Post-Mortem Interval). The cyanogen is very heavy and cannot be thrown far; it's also cylindrical and will roll away easily. There's a couple of very-difficult-to-reverse jumps in Xen, but they either can be reversed or both items can be brought along: in the underground one with the first red tree-root-wire opening a leaf you can crawl along part of the root backwards (it becomes non-clipping quite soon) and barely make a long jump back, and in the one after the tree map opening with a jump to an island with waterfalls and exploding houndeyes you can jump to a side island, throw the hat across (hence this might be impossible with the pizza), jump back, and then jump while holding the cyanogen. At the end of Xen simply throw the hat into the teleporter before jumping in while holding the cyanogen, and the hat and cyanogen will be waiting on the other side, resting on a rock. Carry both of them past the first fight against the Gonarch, and then, after blowing up your first wall, there's a teleporter that the cyanogen can be placed on – you only need to carry the hat after this.

Presumably it's also possible to carry both pizza and cyanogen, but I expect this'll be a bit harder, since the pizza can't be thrown as far as the hat. The battle against the Gonarch isn't that bad, and it's probably easier with the pizza since it doesn't roll around at all.

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posted 2022-10-11, edited 2022-10-23, when i achieved the last of the achievements.

"i'm sticking to you like white on calcium" (scientist line) – does this make any sense?