The following achievements are all related to story progression and can't be missed.

Welcome to Arctic

Star from the screen

Dancing on thin ice

Don't worry if you missed any of these on your first playthrough, you can easily start a new game on the correct chapter and just grab them from there.

Heavyweight target
Kill 5 heavy soldiers.

This one isn't really a secret achievement but is missable, you should easily get it during the first confrontation with Combine soldiers as their are at least 5 heavy soldiers in the area.

Forgotten friend
Find a chumtoad in Xen

Upon reaching this room on Chapter 4...

Climb to the top like you usually would, but instead of going through the portal, look up and use your barnacle to climb up into the small tunnel.

Make your way through the tunnel and reach your old friend, the chumtoad. :)


Worth the wait
Wait... until portal opens

Simply wait in the room behind the door to the left and this one will unlock after a couple of minutes.



First love
Find a portal cube

Upon reaching this room on Chapter 3...

You'll spot this vent to the left.

Go through it and approach the PC.

Press your use key on it (default: e) and it should light up like this.

Now exit the vent back into the main room and you'll notice the cube above you.

Stack some s**t up like so...

Climb up, grab the cube and gain the achievement.


Better looking
Find new hat for Alyx

On the first chapter, upon fighting through all the combine and reaching the elevator, drop on to this floor as soon as you start the elevator.

Grab a box or simply jump up and press your use key (default: e) on this hat to gain the achievement.


Soft Drinks
Is that drink enough soft to you Jolly?

On the first chapter, upon reaching the office complex and fighting through the first group of Combine. You'll notice a soft drinks display cabinet. Just go up and press your use key on the only bottle on the shelf.


Pottatoxed
Find PotatOS in Aperture

On the 5th and final chapter, continue on the linear path towards the end of the game. You'll reach this area. Head to the the end of this corridor and turn left.

Turn left again and you'll notice a small potato hidden within the darkness. Pick up the potato using your use key (default: e) to gain this achievement.




Brain Storm, One benefactor & Universal Soldier
These are currently unobtainable and are planned for a future update, as confirmed by the developer.

If for any reason, any of your achievements aren't working, go to your game directory, delete gamestate.txt and try again. I had this issue with the Better looking achievement and this solution fixed it for me. Default directory should be located at:

I hope people find this guide helpful and if you have any questions regarding this guide, please drop them in the comments. Happy achievement hunting. :)