True, there is much complexity in each of Façade's primary objects, but this necessary complexity is encapsulated in the ideas of Grace, Trip and you. The introduction of the third party is essential here; it is the spark that ignites the play space. Were the play just you and Trip talking, the game would be relatively boring, and the constraints of the AI would become quickly noticeable, as the player's frame of reference casually bounded outside the magic circle. Were there no you, the interactivity would not exist.
With the introduction of the third party, the system dynamics enter a realm referred to by the often-abused term "emergent behavior." In astrophysics, two celestial bodies will circle each other in predictable patterns, but a third celestial body increases the complexity of interlocking motions, the three parties of Façade's drama create a relationship to focus on, constraining the frame of reference and, paradoxically, increasing the room for play within that constrained context. This rule of three is not a coincidence, Sartre's take on hell as a self-perpetuating cell of social suffering depends on the third party to continually interrupt any stable two-person orbit. Hence the phrase: hell isn't another person, hell is other people.
In Sartre's play, hell is an algorithm of social interaction that perpetuates mutual suffering by the confluence of three different people. In games, hell is the uncertainty that the given play loop you're riding will result in an interesting reward, or whether it will continue to throw you into Sisyphus-like frustration. A player of Façade can feel, by the intuitive virtue of the paidic mechanics, after enough play through, a resolution will come to Grace and Trip's existential gripes and save their marriage. When that moment comes, the player is graciously and thankfully shown the door.
Now, if you'll excuse me, I need to get the hell out of here.
Patrick Dugan is a ludosophist. He runs King Lud IC, a blog regarding game design theory, memetics and interactive storytelling. He looks forward to prototyping with Chris Crawford's Storytron, and to pioneering socially-oriented narrative challenge.