For this achievement you have to get all the way through the construction site without using any weapons, yes that includes grenades and Molotovs. Just running and jumping to avoid enemies, kicking them back and making it checkpoint to checkpoint collecting health, it can be done on easy and one player is recommended due to the increase in enemies with more players. Will most definitely take some time and frustration but it is doable.
![](https://i.ytimg.com/vi/pxA6soqr6Ik/maxresdefault.jpg)