Bulletstorm
60 Achievements
1,250
40-50h
No Man Left Behind
Kill all enemies while escaping from the collapsed building
20
How to unlock the No Man Left Behind achievement in Bulletstorm - Definitive Guide
However, this solution needs to be 25 words long, so I would like to wish you good luck on getting 20 easy gamerscore. :)
Act 4 Chapter 3
At the very end of the level a timer will start to count down from 30 seconds. There are two enemies to your right as you make your way to the button you must press. Kick them and continue on. You will get the achievement upon pressing the button.
Obtained at the very end of Act 4 - Chapter 3 where you have 30 seconds to escape from the collapsing building. While you’re escaping you must kill all the enemies in the building. Thankfully there are only 2 enemies that you have to kill. It's possible to miss them if you were focused on escaping instead of killing. Once they're dead enter the train like pod and press the button. Here's a video for demonstration:
Credit goes to Austex3600
Watch the video:
Leave no one behind