Writing with Inform

The creation of textual worlds

Installing Inform can be a little like buying watercolours, brushes and cartridge paper from an art supply shop, getting them home, setting up an easel - and then thinking: now what? Still life, portrait, landscape, abstract? What makes me think I’m an artist, anyway?

An artist's pencils

The documentation included in Inform (and this website) inevitably takes a while to get to the features which really open up the possibilities. So this page is a taste of what you can do with Inform.

Model Worlds

An interactive fiction is a small world, entire of itself, ready for a reader to explore. It might simulate a real place, at a genuine historical period - past examples include the 1893 Chicago World's Fair and the Alexandrian Library in its heyday - or somewhere more fantastical: the planet Mars, in 2150, or a subconscious dream-state. This is a textual world, which is never as literal as a photograph. “A tower that is not stone but slip of pebbles, visible wings of silence sown in azure circles” - words from a poem by Hart Crane, but to Inform, they could make up a “room description”.

Even if the world portrayed is a low-key, realistic background for a modern drama, there can still be a sense of mystery. Because the reader moves from place to place, an interactive fiction reveals its secrets a little at a time: it cannot be read from cover to cover, and sometimes its hidden corners remain undiscovered for years.

Inform allows both broad-brush sketching and finely worked detail. The player who strolls down a railway station platform may read only a postcard-length impression, but a player who stops to examine the train could be told that it is, say, a 6-0-4 steam locomotive. If we need this kind of quantitative detail, we could for instance tell Inform to recognise “6-0-4” as a “Whyte notation” and that “A steam locomotive has a Whyte notation”: then, when creating a new train, we need only say “The LNER Mallard is a steam locomotive. The Mallard is 4-6-2.” (And what Inform can recognise in our design, it can also print out, and understand back from the player’s commands.)

Enough train-spotting. The point is that every work of IF is a model of the world, but each chooses its own aspects of the world to focus on. Most games will never need a kind called “steam locomotive”, much less a concise way to talk with the player about wheel couplings. But every game will need something idiosyncratic. Natural language is a superb tool for adapting to this variety of subjects, and that is what makes Inform so flexible.


Inform makes the creation of these worlds almost as simple as giving directions: "A man called Peter is in the Atrium. North of the Atrium is the Hall of Greek Vases." Inform creates not only things and places, but also connections between them (called relations): Peter is in the Atrium, the Hall is north of the Atrium. The ability to create new relations as needed – for instance, for a game involving detection, “A suspects B” – may be the single most powerful tool Inform offers.

Generalise, Generalise, Generalise

The other great benefit of Inform’s natural language is that allows us to generalise. “After putting a loaded weapon in something which is watched by a policeman...” - now we are no longer talking about specific items, but the sentence reads just as easily, and is just as quick to type. “A steam locomotive can be watered or unwatered. A locomotive is usually watered.” Here we are generalising about circumstances. “Attacking or pushing or pulling something in the Hall of Greek Vases is vandalism.” This time we are giving a name to a whole category of behaviour.

Inform lets us choose the kinds of thing we want to name, the relations we want, the kinds of value we think worth talking about, and so on. When the right concepts have been coined, extraordinarily sophisticated rules can be written in a single sentence.

Tell Stories

A museum trip is interactive, but not fiction: the cinema is fiction, but not interactive.

Most works of IF allow spontaneous exploration, like a museum, but they also have motivation and a plot. The player is a character in a drama, rather than a disembodied observer like the movie camera: he or she is somebody trying to get something done (even if that something is only understanding the situation).

A few books, like John Fowles’s The French Lieutenant’s Woman, and a few movies, like Layer Cake, offer alternate choose-your-own endings, but supplementary chapters and DVD extras can only go so far: we are always aware of the “real” ending. In IF, on the other hand, there can be radical plot variations according to what the player actually does. Many works have multiple endings, and the player may never even realise this.

Just as Inform divides space into “rooms”, it divides time into “scenes”, and its index draws maps of both. Scenes automatically start and end on certain conditions and can lead one into another, or repeat.

Create Characters

The player is a character: and so are the people he, or she, meets. Inform does not pretend to be artificially intelligent. It doesn’t make (many) decisions on behalf of the characters in play. But it does have excellent facilities for letting these characters, at the author’s instruction, do all of the things which the player can do, subject to the same rules.

Moreover, Inform’s “relations” come into their own here: they are the perfect way to describe who knows about what, who has been where, who would like to murder whom. All of this makes it easy to give characters goals to pursue.

Lastly, Inform provides concise but convenient notations for expressing how people react in conversation, something which has traditionally been tiresome to specify in IF design systems.

Build Puzzles

Almost all IF involves putting obstacles in the player’s way, if only to manoeuvre the player through the plot: these are traditionally called “puzzles” - they generally require thought, or a careful choice, to get past. In practical terms, puzzles are solved when the right circumstances are reached. Inform’s use of scenes makes this easy to express: “The Collecting Phase ends when the Gate of Infinity is open and all of the white cubes are in the trunk. The Final Showdown begins when the Collecting Phase ends.”