I would say the first zombie game I played was probably Save the World. Yes, that is embarrassing. Soon after I liked the zombie shooter games and tried 7 days to die and dying light 2. Although I like dying light I prefer focusing more on building mechanics than parkour. That's where my inspiration comes from. I'm building a zombie defense base builder game.
I believe mixing COD zombies wave based gameplay, with crafting and exploring could make a good game. Just like Slime Wars, I hope to take all the good aspects from my inspirations and create a new unique project. I'm currently writing a story for Winter is Here and it's a very exciting thing to write. This project will take probably 2 years minimum to develop based off of current time spent and the scope of the game.
Mixing these genres together well will be hard. Wave based, creates urgency; resources and building takes time. Making the two work together without feeling too strenuous will be something I have to solve. Video Games are a balancing act in almost every aspect. A game can't feel too exciting at a certain point or else everything else will be too dull. One part can't be too boring or that will be the breaking point for a player. Story needs a rising action, climax and resolution. Making a game is hard because everything needs to work well together. A 3D world with a good story is not easy to make.