that’s not really the same as “they said that they would like to use Shepherd again”, is it?
Combine overwiki:
They would [COLOR=‘red’]like to use him again. If they use him or not is yet unkown
same answer as before. the overwiki (that being a wiki can be edited by anyone) says Gabe Newell has hinted that he may one day return. that’s it.
Back on topic.
Оne-time Achievement “Hard to smash”. Achievement requirement - fall from any height and stay alive with only 1% of health.
that’s stupid.
Something in the water: Kill the fish without entering the water on apprehension
The main reason Op4 isn’t entirely canon is because
A) It contradicts HL- at no point after you enter the Lambda Complex labs proper do you see any HECU soldiers.
B ) Race X- they weren’t created by Valve, but by Gearbox. And Gearbox didn’t ask.
C) Having it not canon lets Valve do what they want to with the storyline. However, everything but the scientist dying from mechalite’s post is correct.
Dead operations: Kill all the Black Ops assassins sended to kill you in the chapter apprehension with almost 75% hp or more.
No way out: Kill Nihilianth without being teleported to another room by him.
IMMA FIRIN’ MAH LAZERZ!: Complete the questionable ethics laser puzzle.
That would be fun 
That is kinda hard because the only way to hide from it is to noclip or hide at the bottom of the pit behind a spike… that would be a good achievement 
:lol::lol::lol:
how bout completing the tentacle level, thats worth an achievement!
Docta octoppus: Kill the blast pit tentacles. Here you have it
Maybe a bit more serious
Is that the achievement pic for destroying the citadel or whatever it was? anyways, back on topic. Quick note: I dont expect any of these to be taken seriously
Say Hello to my Little Friend: man a .50 cal and kill 10 soldiers
Look at me!: Jump across the lamda core portal with the jump pack
We come in pieces:Kill a zombie with a rocket launcher
Fish meet crowbar:Kill a fish with the crowbar
Technology hurts: overcharge your tau cannon
Splat: Free-fall and die
Gimme wings: free-fall and survive with at least 10 health.
I hold no grudges: Save all savable civilians.
The Big Race: Complete the final mission in under 4 minutes.
A big problem: survive your first gargantua
BOOM! Headshot…: kill a 20 marines with a single shot to the head.
What Happened!?: Leave the test room after the resonance cascade.
Live Fire Range: Kill 3 enemies in a row without taking any damage
Watch out for the headhumpers Gordon!: Kill a Headcrab while it is jumping in mid-air.
Time Crunch: get out of the garbage disposal unit before any single box breaks. (I am pretty sure the garbage disposal unit is on the end of surface tension, really close to residue processing. Then again, it might be the beginning of residue processing…)
What does THIS button do…?: Push the button to activate the engine in Blast Pit.
More to come if I can think of any… 
Did you dare to spit me in the face?: Kill 20 bullsquids
Sniper no snipin’: Kill all the snipers.
We’re pulling out: Kill all the marines of the game.
I’m the last: Kill Nihilianth.
What Have You Done?: Kill the Gonarch (the achievement name is what Nihilianth says after killing it)
Humilliation: Kill a Hgrunt using only melee
Vort-Essence: Hear barney say something about the smell of a dead vortigaunt.
Today we have cROCKETS for lunch: Destroy the apache.
Sunshine!: Reach the cliff.
Medic!: Kill a H.E.C.U. Who asked for health.
Humilliation. Escory. Crackedback. Unit: Kill 3 Hgrunts in less than 15 seconds.
I love go fishing: Survive against the first Ichtyosaur.
Mentlegen: Kill a smoking marine. (The word mentlegen is Team Fortress 2 Related)
Maybe Black Mesa, That was a joke haha: Accept G-man’s offer.
You choosed bad: Face your destiny after not accepting G-man’s offer.
Unforseen consequences: Find the Scientist hidden in Xen.
I’ma Firin’ Mah Laza! - Retrieve the Egon Gun
MP Achievements
Nuke Em’ All! - Kill 5 People at Once Using The Crossfire Nuke
Release The Snarks! - Release The Snarks in Snarkpit
Clunk! : Kill a turret with a crowbar.
Bullet Time : Do not get shot by a turret in We’ve Got Hostiles
WEEEE!!! : Use a jumper pad for your first time
No Don’t BACKUP!!! : Kill a soldier that calls for backup
KA-BOOOOM!!! : Destroy a tank with the Rocket launcher. while taking no damage from either humans (or aliens) or tank.
It is just a break… : Get transported by Nihilanth an pick up ammo.
Back to kick your… : Find the exit in each of the transport chambers and get back to the main chamber.
RUN FREEMAN RUUUNNN!!! : Get out of the first part of Forget About Freeman without dying once.
MP achievements for a second…:
I would put that in my trophy room… : make 5 kills in a row without dying.
Guess what I did! : Survive an ENTIRE multiplayer match of any sort WITHOUT DYING ONCE.
I am fully charged! : Kill an opponent with a fully charged Tau Cannon blast
Hose 'em down : get 3 kills with a Egon Gun without dying and in a row.
Science is funny sometimes: Use the gluon gun to kill 50 enemies
Rwacket launchar: Get the RPG.
Vagineer was the one who build it!: Destroy a sentry without taking damage (Again vagineer is a tf2/youtube reference)
Multiplayer achievements:
Headless horse- I mean… walkingman: Headshot 20 enemies in a row
Multiple jumping: Do a jumpack jump and then a fully charged shot from the tau cannon before falling.
Aren’t they cute?: Kill an enemy with snarks
M.I.T. Licensed: Use every weapon in a match.
War hero: Kill everyone in a match almost one time.
WEEEE OUCH! Use a jumpack and get killed in the air by another player.
Mission very possible: Find a non-official Black Mesa Multiplayer server. (Modded)
Shark: Kill 5 enemies in the water.
Do you remember where did I put the bloody bombs?: Throw your last grenade and kill an enemy
Fire in the hole!: Use 2 grenades or more to kill an enemy.
They come from the f*ckin’ walls!: Kill 5 enemies with snarks. (Snark pit trap also allowed)
Un-expected: kill a player with a wall mine.
Demoman: Kill 5000 players with explosives in all your playing time.
Sniper: Headshot 5000 players in all your playing time.
Grunt: Use the MP5 to kill 3 enemies without getting killed.
C-c-c-c-combo breaker!: Kill an enemy who had 5 kills or more in a life.
It’s my liiiife!!: Fall doing yourself almost 75% hp damage and kill an enemy without healing.
Doctar!!: Heal yourself to full life when you had 25% hp or less.
The trophy is miiiine!!: Survive a whole match using only the crowbar.
I liek shotgans: Kill 10 players with the shotgun in a row.
I couldn’t live without them: Have 5 Friends from your steam friendlist playing a match with you.
Crossfire: Kill everyone except yourself with the atomic bomb of crossfire.
Did it just explode behind, uh?: Throw a satchel behind an enemy player
Foxtrot uniform: Kill 5 Hgrunt players.
Gordan Freemen: Kill 5 Gordon players.
Security strike force: Kill 5 Barney players.
Tech-no-lo-gy: Kill 5 Robo players.
Rise and shine, mister freeman: Kill 5 G-man players.
Trainer: Kill 5 Gina Players.
With Melee is funnier: Defeat a player with the crowbar while he used it against you too.
Run Mr. Frodo, RUUUN!: Kill an enemy who’s running backwards.
Operation D.e.a.d.: Die in a multiplayer match.
Victory is mine!: end the first in a multiplayer match with 7 players or more.
Judas: Kill a teammate in a team deathmatch game.
Static camper: Kill 7 enemies without moving from your position.
You know that almost no one will read those, don’t you?
Yeah we know. It is just fun to post them lol.
Is this starting to turn into a competition?
Alright, well here i go:
MutliPlayer
I am the FREEMAN!!!: Complete a match without picking up any health whatsoever or dying
Close Encounters: Use only a crowbar, the entire match.
Terrorists Win: Win a match while playing as a grunt.
Braniacs: Win a match as a scientist (freeman, Gina, etc.)
Boom bada boom boom boom! : Use explosives the entire match
Demoman: Use a trip mine effectively
Assault Expert: Kill a soldier with less than one clip of an Smg. (assault rifle if that is what you want to call it)
That Guy right there…: get 10 revenge kills in one match.
Launch Torpedoes!: Kill someone with a RPG while you are under water.
Gunslinger: Complete a match with any pistol. NO RIFLES OR EXPERIMENTAL WEAPONS.
YOU Failed: Complete a match without getting a single kill.
Vasili: Kill a soldier with a single crossbow shot to the head. (named after the famous Russian Sniper that was a hero during WWII. My favorite soldier EVER!)
Backstabber: Kill a player from behind with a crowbar.
SANDVICH!!! : Pick up more than 20 health packs in one match.
F*ck you: Teabag on a dead player.
Technology wins: Play a match as Robo playermodel.
ALIEN ALERT!: Kill a vortigaunt before he can start attacking.
Boom Hedshot!: Use only the crossbow to kill for an entire level (in singleplayer) or a row (in multiplayer)