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§3.7. Lighting

At any place (room, or inside a container) light is either fully present or fully absent. Inform does not usually try to track intermediate states of lighting, but see The Undertomb 2 for a single lantern with varying light levels and Zorn of Zorna for multiple candles that can be lit for cumulative changes to the light level.

Light can be added to, but not taken away: rooms and things can act as sources of light, by having the "lighted" and "lit" properties respectively, but they cannot be sinks which drain light away. The reason darkness is not a constant hazard in Inform-written games is that rooms always have the "lighted" property unless declared "dark". (We assume daylight or some always-on electric lighting.) A "dark" room may well still be illuminated if a light source happens to be present:

The Deep Crypt is a dark room. The candle lantern is a lit thing in the Deep Crypt.

Hymenaeus allows us to explicitly refer to torches as "lit" or "unlit", or (as synonyms) "flaming" or "extinguished".

For light produced electrically we might want a wall switch, as in Down Below, or a portable lamp, as in The Dark Ages Revisited.

The fierce, locally confined light thrown out by a carried lamp has a quality quite unlike weak but ambient daylight, and Reflections exploits this to make a lantern feel more realistic.

When the player experiences darkness in a location, Inform is usually very guarded in what it reveals. ("It is pitch dark, and you can't see a thing.") Hohmann Transfer gives darkness a quite different look, and Four Stars heightens the other senses so that a player in darkness can still detect her surroundings. The first of the two examples in Peeled allows exploration of a dark place by touch.

It is sometimes useful to check whether a room that is not the current location happens to contain a light source or be naturally lighted. This poses a few challenges. Unblinking demonstrates one way of doing this, so long as there are no backdrop light sources.

Cloak of Darkness is a short and sweet game based on a light puzzle.

* See Room Descriptions for an item that can only be seen in bright light, when an extra lamp is switched on

* See Looking Under and Hiding for a looking under action which is helped by the fiercer brightness of a light source

* See Going, Pushing Things in Directions for making it hazardous to walk around in the dark

* See Electricity and Magnetism for batteries to power a torch or flashlight

* See Fire for a non-electrical way to produce light

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*ExampleThe Dark Ages Revisited
An electric light kind of device which becomes lit when switched on and dark when switched off.

Understanding "flaming torch" and "extinguished torch" to refer to torches when lit and unlit.

Emphasizing the reflective quality of shiny objects whenever they are described in the presence of the torch.

Two different approaches to adjusting what the player can interact with, compared.

**ExampleDown Below
A light switch which makes the room it is in dark or light.

**ExampleThe Undertomb 2
Flickering lantern-light effects added to the Undertomb.

**ExampleHohmann Transfer
Changing the way dark rooms are described to avoid the standard Inform phrasing.

Finding a best route through light-filled rooms only, leaving aside any that might be dark.

***ExampleZorn of Zorna
Light levels vary depending on the number of candles the player has lit, and this determines whether or not he is able to examine detailed objects successfully.

***ExampleFour Stars 1
An elaboration of the idea that when light is absent, the player should be given a description of what he can smell and hear, instead.

****ExampleCloak of Darkness
Implementation of "Cloak of Darkness", a simple example game that for years has been used to demonstrate the features of IF languages.