Project Zomboid Mod: They Knew

They Knew is a mod I created for Project Zomboid around a simple question: what if there actually was a cure for the zombie infection, but getting it meant risking your life?
Rather than putting a cure into ordinary medical loot, They Knew introduces an extremely rare special zombie carrying Zomboxivir, an experimental medication capable of purging the zombie infection. Finding one can turn what would normally be a death sentence into a desperate hunt for the one thing that might save your character.
The rarity was deliberate. I didn't want a cure to simply remove one of Project Zomboid's most important threats. It needed to create a new story. Getting bitten doesn't mean you're safe because you installed the mod. It means you suddenly have a reason to take enormous risks while the clock is ticking.
The mod also introduced its own hazmat suit, satchel, configurable sandbox settings, and Zomboxycycline, a preventative medication that can temporarily protect a character from infection. Later development expanded the medication system and the larger mystery surrounding exactly who "They" are and why they were present during the Knox County outbreak.
Apparently that idea resonated with people.
The original Build 41 release grew to more than one million Steam Workshop subscribers, thousands of ratings, tens of thousands of favorites, and hundreds of thousands of Workshop collections. Other modders also created add-ons and integrations built around it.

What's Next

I'm currently working on They Knew Expanded, a major evolution of the original mod for Project Zomboid Build 42.
The original idea of hunting for a cure is becoming part of a much larger system built around the mystery of who "They" actually are. The expansion introduces competing offscreen factions, reputation, collectible evidence and lore, new infected characters to hunt down, radio-delivered quests, additional equipment and medications, and a new Dead Drop system that lets players secretly trade with groups operating outside the quarantine zone.
The goal is to make the mystery behind They Knew something the player can actually investigate and participate in, while creating new reasons to explore the world and collect things that would normally be left behind.
It's substantially more ambitious than the original mod.
They Knew Expanded is currently in development for Build 42. I'm deliberately waiting for the game's multiplayer environment to stabilize before releasing it rather than rebuilding major systems every time the underlying game changes.
More is coming. They knew the whole time.