G-Force
44 Achievements
PS3
Marching Agent
Walk more than 20km with Darwin
12.3%
How to unlock the Marching Agent achievement in G-Force - Definitive Guide
If you save your game before any of the RDV missions (I chose RDV Escape) you will be in a vehicle traveling pretty fast. Reload the save once you're done with the level and play it again until you get 25km with Darwin. I got it on my 2nd try in RDV Escape which takes only a few minutes to complete.
You can easily get this if you are going for the second play through achievement. Otherwise, you can use any of the sections where Darwin has to go over a treadmill - just run along the treadmill at it's same speed and eventually it will pop - probably later in the game though.
I got mine during the middle of the second play through.
I got mine during the middle of the second play through.
You should have this by the end of the game, but if you don't just walk around in the second to last level until you do unlock it. (In the very last level you will not be able to play as Darwin, so you need to this before you start the last level.)