Should you be feeling a little disappointed by the zombie themed Man vs. Machine mission added for this Halloween, fret not! There have been a few settings added that allow for a slightly more authentic zombie survival experience, provided you're willing to fiddle with the console. These zombies are apparently immune to headshots and backstabs, and only use melee attacks. Also, their AI makes it so they only charge at the player(s) on the shortest path available, but due to its simplicity allows for dozens to be spawned at once. Credit to Ripper Roo on Facepunch for the screen, and Ned_Ballad for quoting the Steam Forum post.