uncut rock
For example you could choose certain events for a map that make it harder then just playing it normally, like one event could be a big horde (kinda like days gone style just not full of runners bc no one will survive that encounter)that just shambles around the map hive mind style but can be avoided by waiting for them to pass or go around them, and alerting a zombie from the middle of the horde or from the front of the horde could pull all of them down onto your position but alerting one from the back would just pull that singular zombie onto you or just a small handful of them onto you (unless it's like a gunshot or somethin very loud or audible) it would help with map replayability and the horror aspect of the game but you would have to rely on your teammates to not get everyone killed because if someone starts getting chomped well, if you know you know..
Stealing the idea from someone else's post, blackouts could be another event thing and maybe a timed event where the city gets fire bombed and you only have a certain amount of time to make it out just a few sleep deprived ideas maybe event isn't the word I'm looking for but eh wtv bad sleep schedule so bad communication (and hordes should be escapable and the loud noise of them chasing a player would make it a cool addition to bring surrounding zombies down on top of the players as well so you have to preplan escape routes)
