Already got Episode One/Two Achievements? Here's How To Get Them Back On Half Life 2 (20th Anniversary Update), Instantly!

This is a LEGAL (as far as achievement hunting websites go) method to do this, it's extremely simple.

Step 1) Install Half Life 2
Step 2) Find Half Life 2: Episode One in the Store
- For this, I recommend typing "Half Life 2: Episode One" in the store and clicking on the soundtrack.
- A purple bar towards the top of the soundtrack's description will have a clickable "Half Life 2: Episode One" link.
- Click this link, it should take you to the store page of Half Life 2: Episode One
Step 3) Click "Play" on the open store page. This will take you to the main menu of Half Life 2: Episode One.
Step 4) Re-do Steps 2 and 3 for Half Life 2: Episode Two
Step 5) Open Half Life 2.

All your previously gained achievements should pop up now!

Hope this was helpful. Don't worry, I was also panicking when I saw all the merged achievements greyed out. I like Little Rocket Man in concept but...come on Gabe.