(this summery doesn't do it justice on how customizable it is and all the features included Its really really good) This one spawns NPC,s around your character at somewhat randomized intervals like left 4 dead style. You can have an all out war between factions in the middle off your zombie apocalypse or you can use it to add to your zombie spawns.
Warlike does a lot of different things really really well. Then Zombie walkers - this will spawn ghouls/zombies as well, but lets you control your spawns as well as attacks on settlements, disease converts dead NPCs into zombies, bunch of other fun options. The running dead - this one places hords of Ghouls /zombies all over the map. Or if I want to play the main quest without the Minute Man Then I'll use Wasteland Operator when I don't want to play through the main story. (full disclosure the next two mods are my own) After a while of playing it I missed the questing and friendly NPCs and hunted around for alternatives here is my build with links.
It turned into a pretty good sandbox zombie shooter. Now SKK made a great zombie shooter that started as a rip on fallout 76. I thoroughly enjoy the modabilty of Fallout 4, my personal setup for playing through the story line or a variation of it is a zombie apocalypse.
