Facade - a one-act interactive drama. Sounds interesting.
"Facade calls itself a one-act interactive drama, and is an attempt to create realistic 3D AI characters acting in a real-time interactive story, where you can talk to them via a natural language text interface. The player is cast as a visiting longtime friend of Grace and Trip, a couple in their early thirties, and ends up in a verbal crossfire resulting from their failing marriage." (via Slashdot)
It's available as a free 800MB download, or on 2 CDs by mailorder.