Façade

Played in a first-person perspective, the game is set in an apartment where the player can move around freely using the keyboard. Prior to starting the game, the player also selects a name from a list, which is reflected in how the game's two characters, Trip and Grace, address them. Players interact with Trip and Grace using text input to speak, or can use the mouse to select parts of their body to interact with, including options to comfort, hug or kiss the characters at any time.

The game uses natural language processing, identifying certain key words in player input and deducing its context, to influence the conversation and the reaction of Trip and Grace to the player's conduct. The couple can react to these in several ways, such as laughter, excitement, surprise, and anger. If the player behaves inappropriately, Trip and Grace react with great offense. Persistent rudeness can lead to the player's removal, and so does excessive physical intimacy.

Façade is an interactive drama video game, structured as a one-act story about a married couple, Trip and Grace. The player assumes the role of a long-time friend, invited for an evening get-together at the couple's apartment in New York City. At first, Trip and Grace are friendly, but they become hostile as the player witnesses the devolution of their marriage.

The game begins with a black screen and a voiceover from Trip, who is calling the player to invite them to the apartment. After the player has chosen their name, they spawn in front of the door, overhearing an argument between the couple. Afterwards, Trip opens the door and lets the player inside. The player can discuss various topics with Grace and Trip during their stay, such as the couple's recent vacation in Italy, the drinks Trip prepares at the bar, and Grace's attempts at redecorating the apartment. Other subjects of conversation can be about their work, hobbies, families, sex life, or the prospect of their divorce.

Mateas co-developed Façade with Andrew Stern over five years, self-funded and with a limited budget. Prior to development, Mateas was a doctoral student at the Carnegie Mellon School of Computer Science, and Stern was a programmer and designer on the virtual pet video game series Petz. Mateas and Stern met presenting at a series of conferences on the intersection of artificial intelligence and interactive entertainment, and began initial work in 1998 on a long-term "interactive drama piece" and "commercial product prototype".

In 2000, Mateas and Stern formally commenced a full-time collaborative project to "build an interactive story world integrating believable agents and interactive plot", with a plan to create a game around a "domestic drama in which a married couple has invited a player over for dinner." To develop organic and believable character behaviors, Mateas and Stern developed a complex programming framework named "A Behaviour Language" to program and organize the expressions of multiple characters as "believable agents", and a "drama manager" to organise events in the story to guide the interactions towards a tension and resolution of the plot. Façade was released for Windows in July 2005 as a free download from the developers' web site.

Many critics gave Façade positive reviews at the time of its release. Several publications like NBC News, The New York Times, Newsweek, and The Boston Phoenix praised the game for its technical achievements, writing that it was an important step for the evolution of video games, interactive entertainment, and AI. Gamasutra wrote that Façade was "one of the most important games ever created, possibly the most important game of the last ten years," above The Sims and Grand Theft Auto. The reviewer, Ernest Adams, called the game's design "revolutionary" and "technically ambitious", listing five areas of technical achievement: its natural language parsing and conversational interaction, natural language generation, emotional modelling, facial expressions, and body language. The Economist mused: "as graphics improve, artificial intelligence is becoming an ever more important part of designing video games."

Critics also wrote about how the game handled its characters and story, and they also found its attempts innovative. Adams praised Façade for being unlike most video games at the time, highlighting its lack of a victory condition and focus on personal relationships that he found believable. Many others said that Façade showed, with complex AI, that video games could be just as compelling when they are character-driven instead of action-driven. As Set Schiesel, who did the New York Times review, wrote: "[this] is a future where games are driven as strongly by characters as combat [and] as much soap opera as shooting gallery".

Retrospective assessments of Façade have recognized the game's technical achievement in its application of artificial intelligence and popular appeal. Describing the game as an "important research and cultural milestone", Game Developer, formerly Gamasutra, identified Façade as a project that made an "indelible mark on video games" due to the uniqueness and complexity of its design of artificial intelligence. Similarly, The Guardian cited Façade as an "interesting" milestone and "fascinating experiment" in the advancement of emotional artificial intelligence. The game was also recognized to have attracted mainstream attention, unusual for an independent video game at the time. Rock Paper Shotgun noted the game "was cutting edge enough to warrant scientific papers being written about it, but playable and interesting enough to be spread around the games world".

Throughout the decade since its release, Façade developed a cult following and spawned several Internet memes, largely due to "Let's Play" videos on YouTube that exploited Grace and Trip's awkward reactions to what the AI deemed inappropriate behavior, which was sometimes nonsensical. Many high-profile YouTubers at the time accrued millions of views on their playthroughs; PC Gamer attributed the game's "second coming as an Internet meme" to PewDiePie's first video about the game, which garnered over seven million views, and also named Jacksepticeye and The Gaming Lemon as further contributors to increasing Façade's mainstream exposure. Game Developer commented that "arguably [Façade's] biggest impact is that people know what it is outside of the academic conference circuit".