Apparently this achievement (and it looks like others) are linked to a real-world scavenger hunt that the developers set the players on. Based on a forum post here, where people had been aggregating data, the way to unlock this specific achievement is this:
This is amazing! birdfeet's image had three symbols on it, which brought us up to 9 total.
I played around with different code combinations and finally found the one--or, at least, one that gave a response and also unlocked the "Walk Your Own Path" achievement.
Spoilers for the code and what it gave me:
If you number the symbols on the keypad 1-9, with the upper-left (left slash) being 1 and the bottom-right (E with dot) being 9, the code was:
After [being input], a black screen with Land Sliders / Prettygreat appeared, along with the achievement. And this:
That looks like a website address? But maybe in code? If so, I have no idea what it translates to. Another puzzle??
Image of the page that appeared:
This article does a good job summarizing the entire adventure these players went on. Unfortunately, the "game" is now over, but the code above is what you need to unlock this achievement.