There’s only a couple achievements to be aware of before beginning the game. First, there is an achievement for smashing 50 glass bottles so make sure to smash every bottle you see for the first few chapters of the game. This achievement counts across save files, unlike in past Half-Life games with stat-based achievements. Second, there is an achievement for bringing a gnome from start to finish, just like in Half-Life 2: Episode Two. I have indicated where you can find this gnome in big bold text under the Chapter 1 section of this guide.
Chapter 1: Entanglement
One thing to keep in mind before beginning is that there is an achievement called Mazel Tov which will require smashing 50 glass bottles. This won’t be your first achievement, but I’m going to list it first as the time you unlock it at can vary greatly.
Pick up and smash 50 glass bottles.
Throughout the game are many, many glass bottles. The first chapter has a bunch, so smash every single one you find. You will likely get this achievement a little into chapter 3. I won’t list a bunch of locations, as they are very easy to find and it doesn’t matter whatsoever if you miss any. In fact, you can start a new save file and smashed bottles will still add to your stat.
Feed the snark.
In the very first room, there is a snark trapped in a little glass tank. It looks just like the achievement icon. To its left is a food container; dump some into his tank and the achievement will pop.
Hit and Run
Break out of the Combine prisoner transport vehicle.
Storyline, cannot be missed. Unlocks after you exit the crashed prisoner transport vehicle and walk into the streets.
On a Roll
Interact with the playground somehow
This achievement we’re still a bit unsure how it functions. I picked up a red bucket nearby and rolled it down the slide; I’m unsure if that’s what made the achievement pop, though. I also spun the merry-go-round, went down the slide (more like walked), spun all of the tic-tac-toe blocks, and jumped from tire to tire. Further testing is needed on the behavior of this unlock.
Represent yourself with a specific prop on Russell’s map
In Russell’s room, there is a miniature baseball character (the one in the achievement photo) located in front of a monitor to the right of the door to the gravity gloves. You must put it as your representation in the minimap when Russell asks you for an object.
Catch Russell’s ammo magazine before it hits the ground.
When you first go outside, Russell will throw a gun out the window for you to catch. Don’t worry if you miss. After he throws the gun, he’ll throw you a magazine, and you need to catch this in mid-air. It’s not too hard, but if you miss, you need to reload a previous save.
At the very end of Chapter 1, in the area where you first get the gun, do NOT go on the train yet! There is a gnome here, and you need to bring it to the end of the game for the Gnome Vault of My Own achievement. You can either do a second playthrough on story mode to speed things up later, or grab it now and just do a single playthrough of the game.
Chapter 2: The Quarantine Zone
Chapter 2 begins when you wake up on the train.
Loot a corpse.
This one is practically unmissable; anyone playing this game is going to be needing all the ammo they can get. Simply use the gravity gloves to take an ammo magazine off of a dead body at some point. There are plenty of opportunities throughout the game to do this, but the first is just past the first resin in the game, where there is a dead body in front of a padlocked door. On a sidenote, make sure you grab all the resin you can across the game, checking every corner.
Enter the Quarantine Zone.
Storyline, cannot be missed. Unlocks right after entering the Quarantine Zone, which has a giant door you unlock with the first puzzle in the game.
Smash and Grab
Break open a supply crate with your hands.
Another practically unmissable achievement. The first supply crate in the game is in the trains, at the start of the Quarantine Zone. In one of them is a ladder you are required to use to progress, and next to it is a supply crate. Smash it on the ground and the achievement will unlock. Also probably loot it. Ammo is important.
Up in Arms
Install your first pistol upgrade.
Right after a very intense train combat section is a room with some lockers and an upgrade station. You’ll need 10 resin; you should hopefully have this much if you’ve been looking, but if not, it’s okay as there’s plenty of other upgrade stations across the game you’ll encounter. Complete the puzzle, put your gun into the station, and buy the cheapest upgrade (Reflex Sight).
Receive a tasty treat.
Storyline, cannot be missed. This will pop at the end of your vortigaunt encounter. He will throw you the corpse of a headcrab and say his “sustenance” line.
Chapter 3: Is Or Will Be
Chapter 3 begins just after the meeting with the vortigaunt.
Zombie with a Shotgun
Collect the shotgun.
Storyline, cannot be missed. Unlocks right after grabbing the shotgun with your primary hand (make sure your primary hand is free for this).
Enter the explosive Xen infestation.
Storyline, cannot be missed. Unlocks after you get the red valve and exit the Xen Garden area (this is the area with all the explosives you have to avoid).
Kill a grunt by shooting their gas tank.
You can first get this in the section where you first engage in combat with the combine outside. All of the combine have gas tanks on their backs, which you can shoot to instantly blow them up and unlock this achievement.
Off the Rails
Stop the prisoner transport train.
Storyline, cannot be missed. Unlocks after you’ve crashed the train and it stops completely.