On the PS4, Zombi is a great game and I think only like $20. It was originally on the WiiU as ZombiU, but they ported it to the PS4 and changed some of the control schemes to allow it to run without the gamepad.
Zombi is more survival horror that runs through its story, no side quests. They did a really good job of capturing the isolation of a zombie infested city. Supplies are scarce, ammo is limited, single zombies are a threat and anything more than one can easily get you killed. It's perma-death, and after each death brings on a new survivor with reset skills and no equipment so you have to go on corpse runs to find your zombified remains and get your gear back. It makes it really intense searching new areas knowing that any mistake can end your run. Skills were easy enough to rebuild since they were weapon proficiency, but that meant spending more ammo to build which is already rare to begin with.
The only real complaint is the melee combat is clunky, and since you try not to run around with tons of ammo on you, you end up falling back to melee quite a bit. I didn't do a full run through on the PS4, but the ported version has new melee weapons that I didn't really get to use.
Not on the PS4, but I really liked State of Decay. It was more of a simulation since you built bases, collected survivors, managed resources, and built supply lines. You would take survivors and run missions to progress the story, but it was open world so you can just go of the story and go on supply runs and bolster your defenses.
The game definitely had its faults. It was buggy, combat was clunky, sidequests were repetitive fetch quests, and there was pretty much no story. Even with all of it's faults it had a lot of interesting game mechanics and I'm really excited for the sequel they announced at E3 so they can fix some of the faults and expand on the more interesting features.
