I'm a big fan of the zombie survival type,
But there is a big problem with this type of game, it's the boredom.
You arrive on the game all happy, you discover the features, you looted, you found a base, you go to get weapons and you die.
Then you start again, you appear elsewhere, you looted, you find a base, you go to seek weapons but .... this time you do not die.
You continue to play, you have a lot of food, a lot of water, a lot of ammunition, and suddenly, you have a feeling that invades you, which is called boredom. That you no longer have a goal, you already have everything in your base that you have reinforced, you no longer fear anything.
You have to avoid that!
And I think, personally, that only one game (also, ugly, buggy, bad and technically late speak that it has) has succeeded, and it is 7 days you die.
In my opinion, it is mandatory to have this feature of horde that comes on you every x days!
In my opinion, it's one of the only thing that makes that you can't really turn around, and that you can't say that you don't have any objective anymore because you're always preparing for the next horde and there's a pressure that is created!
With this feature, the end of the game is when you have been destroyed by a zombie horde and it seems complicated to rebuild everything.
This is in my opinion THE FEATURE that ALL zombie survival games should offer.
If I had the money, the development skills and so on, I would have made my game like that 🙂