Game Theory

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Spacewar! Dan Edwards ’59 and Peter Samson ’62 demonstrate the first interactive video game on MIT’s PDP-1 in the early 1960s. Credit: Courtesy of the MIT Museum

Such is one possible beginning to Planetfall, a classic ­interactive-fiction game written by Steve Meretzky '79 in the heyday of Infocom, a Cambridge-based software company founded by MIT faculty and alumni in 1979. In interactive fiction, the direction of the story hinges on input from the reader; the ending or other events may change depending on what the reader does. The player controls a character, typing in commands that dictate that character's behavior whenever a decision point is reached. Often, traversing an entire game and reading the whole story requires the player to solve a series of difficult puzzles.

Nick Montfort, SM '98, an assistant professor of digital media at MIT whose book Twisty Little Passages traces the history of interactive fiction, calls Infocom the Shakespeare of game writing. In Planetfall, Meretzky, the company's most prolific writer, introduced Floyd, a robot helper who traveled with the player. Unlike the wooden characters then typical, Floyd was charming, vivid, and clever. He would tease the players, who tended to save the game to disk before actions that could get their character killed; saving would prompt him to say, "Oh, boy! Are we gonna try something dangerous now?" His selfless actions also became key to the game's plots.

In the 1980s, Planetfall and other Infocom text adventures were as revolutionary as the flashiest work of Harmonix is today. Infocom's software made more sophisticated use of the PC's processing power than common programs such as word processors, explains Montfort. Although the company's games weren't the first works of interactive fiction, Montfort says, they brought major technical and stylistic advances to the field.

Infocom had its roots in a game called Zork, built on a mainframe at MIT starting in 1977 by Marc Blank '75, Dave Lebling '71, SM '73, Bruce Daniels '71, SM '74, and Tim Anderson '75, SM '77. Players of Zork explored an enormous cave, searching not only for treasure but for the remains of an ancient civilization, described in chunks of text peppered with geeky in-jokes and references to MIT. While the game itself referred to its parser, which was responsible for interpreting player commands, as "fairly stupid," it was actually able to handle more complex sentence structures than earlier games could. The group also created a fantasy world that was more sophisticated than any seen before: objects such as vehicles could move within it, and other characters could interact meaningfully with the player's character. When the group started Infocom a few years later, the technological innovation continued.

The company developed advanced compression techniques to fit large quantities of data on disks whose capacity was tiny by modern standards. (At the time, a typical home computer had one 100-kilobyte floppy drive; today, even Apple's smallest iPod has a one-gigabyte hard drive, or more than ten thousand times the storage capacity.) To build the PC version of Zork, Infocom also created the Zork Implementation Language (ZIL), a new programming language based on the MIT Design Language (MDL) used in the Dynamic Modeling Group at MIT. Using ZIL, programmers could write instructions that read more like English than instructions written in other languages, making programming easier.