This concept for Half-Life 2 was an interactive item that I also modeled- designed to chop up zombies as you make your way through the creepy and overrun Ravenholm map. Circa 2001 or 2002-ish
This was one of the very first pieces I ever got to concept that made it into the game. It's a propeller trap for chopping up zombies in Half-Life 2's Ravenholm level.
The piece shows up in Valve's behind-the-scenes book: "Half-Life 2 Raising the Bar"