I think a lot of the players are looking for a challenge when playing in nightmare mode, and I'm included. But we also seek a classic apocalypsis to say:
1. Without monsters that only ruin the immersion in the apocalyptic world. Make the hordes of zombies much more lethal, much bigger, let the noise of the horde attract more zombies and make it crazy!
2.That there are more hostile communities on the map, trying to subdue other communities to work for them, try to steal your food, weapons, or ammo, or just try to kill you by going to attack your base. So you also have to worry about the living, not just the dead.
3. That your community can still do the same, go attack other communities, subdue them, rob them or just kill them for the simple fact of wanting to do it to feel power. This could lead to inter-communal wars, as well as inter-community alliances with common enemies.
4. That a headshot is a shot in the head and do deadly damage, either to yourself to an enemy.
5. That the doors and entrances to the community base, can be blocked as well as the windows could be locked in State Of Decay Year One.
6. That communities can be larger and more numerous and that the bases can be cleaned and customized. Being a larger community, it will allow some characters (2 or 3) to live and take care of the outposts that are in control.
7. That there are family ties such as father and son/daughter, brothers, and that they can form loving bonds between characters, that they can fall in love and have a relationship so that this increases the morale of the survivor. It would also make the loss more tragic if he died.
8. Let him let you personalize your own character so you can embody your own apocalypse and thus delve deeper into the game.
Everything would be more diverse if there was the option "create your own apocalypse" and not only choose the difficulty. So you could perzonalize whether there are monsters or not, the damage of the zombies, the size of the hordes, whether there is a cure to the blood plague or not, among several more options, that would allow each player, enjoy the game in their own way.