I want a zombie survival game that has
1) huge modern city maps with usable buildings that spans from downtown to the suburbs and out into the country/forest.
2) Total free roam mode.
3) Fully customizable characters, and tons of gear to pick up and upgrade and customize.
4) wide range of weapons and customization and upgrades.
5) vehicles that don't break the game. (the aren't usable everywhere, needs fuel, attracts zombies.)
6) day/night cycle and weather.
7) random npcs to meet in the wild that can give you quests, be hostile, ignore you, give advice, or be recruited, etc.
Be able to build a base almost anywhere and customize it and upgrade it. Maybe turn a house into my base or make the penthouse in a skyscraper my base.
9) Co-op and op-in pvp.
10) 1st and 3rd person view.
11) A combat system like Dying Light/Dead Island and have takedowns like Dishonored/Far Cry where you go into an animation.
12) unique gameplay elements like using dead zombie guts to gain temporary invisibility from zombies, or setting up a security system for your base that with the camera feed viewable from inside your base, unique crafting system, message system like Dark Souls, and be able to invade peoples worlds as a special zombie.
13) weekly and daily events that give special rewards.
14) real horror moments and crazy awesome moments.
15) procedurally generated content like items in houses or certain areas change each time you go there, or "dungeons" that are unique areas that you have to get through to gain rewards.