Zombie Game 2
Here's the game "in action". It doesn't really do anything yet. Basically you can run around and the zombies will head in your direction.
My initial idea was Multiplayer Gauntlet with Zombies, but I recently learned that Torque Game Builder only supports turn-based multiplayer games. I suppose there's always their 3D engine, but there's already a ton of zombie first person shooters out there.