Undead Labs CEO Jeff Strain (with an assist from design director Richard Foge) was kind enough to share a few new pieces of concept art and answer some of our questions about the sequel, which will support four-player co-op.
Speaking of friends, we asked Foge if your friends could suddenly decide to be un-friendly, considering the fact that State of Decay is all about managing your relationships with your fellow survivors.
“The primary goal for multiplayer is that other players bring an interesting new dynamic to the simulation," Foge said. "The heart of State of Decay is consequences, and we need to make sure that other players are more than just an awesome addition to moment-to-moment gameplay; they need to become a part of the story based on the agency they have in your world.
“Your guests cannot just say ‘screw it, I'm taking this to PvP-town!’ and directly attack you or any of your community members, because State of Decay 2 isn't a PvP game. They can't go into your base and tear down all of your facilities. But there are plenty of ways that they can be a hostile force in your world because they can directly affect the simulation in meaningful ways.
"The simple example of this is someone making noise and the zombie simulation responding. You may find yourself in a situation where one of your characters ends up getting killed because your guest made a racket that you couldn't deal with. This goes both ways though. You may end up causing a situation that gets one of your guest's characters killed, permanently.
“A more complex example is killing enclave NPCs that aren't a part of your community. There might be great reasons for them to kill those characters or they might just be going Westworld Blackhat on your simulation, but either way you are going to have to deal with the consequences of those actions. In the case of killing members of an NPC enclave, your relationship with that enclave is most likely going to become incredibly hostile and they may attack your community on sight. Now you have to decide how you want to handle that situation.”
"We want it to be fun to play with your friends, so the design mechanics encourage teamwork and cooperation," he told us. "That said, 'encouraging' is not the same as 'forcing.' You will be free to get in a car and go anywhere you like, just as you would if you were playing by yourself."
"There may be times when it’s tactically advantageous to do so," he continued. "For example, you may be under the gun to get medical supplies back to your base, and you decide to split up and have two players scavenge the supermarket pharmacy while two others go scout for a car or SUV with a large amount of trunk space to get the goods home. Or you could even be working on completely separate objectives and only come together as needed to get each other out of a tight spot. Ultimately you’ll be more effective (and, if we do our jobs well, you’ll have a lot more fun) playing close together, but as always with State of Decay, your play style is up to you."
Excited for this game. 
