Co-Optimus says: “When Rebellion released the free ‘Left 4 Dead Character Pack’ for Zombie Army 4 in June, we suspected that it was only a matter of time until a character pack with the Left 4 Dead 2 characters followed. That has now come to pass – the new free DLC pack adds the four Left 4 Dead 2 survivors to Zombie Army 4 as playable characters. We played through a campaign mission with the new characters to bring you these screenshots and impressions.”
Source: N4G PC Hands On With the 'Left 4 Dead 2' Survivors in Zombie Army 4 [Co-Optimus]