Line of Sight

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The requirement of having direct view from one game element to another.

Many of the actions done in games are done through avatars or units, and these may diegetically not be able to perceived the game state in the same way as the players controlling them. When the avatars and units can only act on things they themselves can perceive this is most often determined if they have a clear Line of Sight to that which they wish to interact with.


Most Miniature Games and tactical Wargames, e.g. Warhammer 40K, Advanced Squad Leader, and Memoir '44, require that firing units have clear Line of Sight to their targets. This is in many cases not only dependent on the absence of buildings, rubble, and blocking vegetation but also the ground itself when the battlefield has height differences. Units excepted from having to have Line of Sight include artillery and other units capable of indirect fire, but these may require having other units spotting for them.

In Frag avatars can only shoot at the other avatars which are not hidden behind walls.

Just Cause 2 lets players shoot with grappling hooks at anything they can aim at in order to move there, or draw items and people towards the players' avatars. Several mods to the Quake series include similar grappling hooks to make movement easier. The Legend of Zelda series also contains grappling hooks but only lets players hook onto specific parts of the game world with them. The Portal series lets players shoot portals to whatever part of a level they can see (except through some types of glass), and can then move there by entering the matching portals.

Using the pattern

Line of Sight is typically used as an requirement to perform actions. A basic requirement for Line of Sight is that there are things can see, typically Agents such as Avatars or Units, so making use of the pattern requires choosing how each of these are affected by it. Typically all makes use of it in some sense but varying how it is applied, e.g. that some Units can ignore some Environmental Effects, is a way of providing Privileged Abilities to these.

First-Person Views is an easy way of introducing Line of Sight for what can be visually perceived, but it can also be used to affect gameplay actions. The action of Aim & Shoot is probably the most obvious example of this; it should be noted that in addition to Aim & Shoot instantiates Line of Sight, Line of Sight can modulate Aim & Shoot since being able to aim requires being able to have Line of Sight. While this may seem redundant, Vision Modes may modulate how Line of Sight works and in turn affect if Aim & Shoot is possible or not.

As the Aim & Shoot case shows, Line of Sight can be used to modulate Combat, but it can also be used as a part of Movement (e.g. the use of grappling hooks in Just Cause 2 or the portals in Portal). For Combat, the use of Line of Sight opens up for the possibility of having indirect fire as Privileged Abilities, although they may still require Line of Sight from others. All these examples are also examples of modulating Aim & Shoot, but Line of Sight may also be used to trigger Automated Responses from Traps or waiting Agents and this can be used to modify Evade and Stealth goals.

Line of Sight requires that there is something that can block it in the Levels or Game Worlds, and this is typically Environmental Effects, Obstacles, Diegetically Tangible Game Items, or simply walls. Big Dumb Objects can be said to instantiate Line of Sight since they usually can be seen from large parts of Game Worlds. Providing good Line of Sight from some parts of Game Worlds but not others are part of creating Sniper Locations and Strongholds. Avatars and Units may also block Line of Sight but only do so temporarily.

As a contrast to using Line of Sight to affect information or actions, the presence of Line of Sight in a game can also be used to create Alignment goals.

Diegetic Aspects

Although Line of Sight does not usually need to be visualized in Game Worlds since it represents seeing rather than something than can be seen, some Traps than make use of Line of Sight can be diegetically motivate, e.g. laser beams or even trip wires.


When applied to Units or Avatars under players' control, Line of Sight changes their Focus Loci and thereby how they have to relate to Game Worlds and Levels, and what is in them. Since it requires players to consider spatial relations from specific point of view in the Game Worlds, Line of Sight can encourage Spatial Engrossment. It is more or less a requirement for Game World Navigation to be necessary at all but how difficult this activity is depend heavily on how often players can have Line of Sight to game elements, where Landmarks are the most important. It is very often used to control the extent of Fog of War.

When Line of Sight is used to create ways of failing with Stealth goals, it leads to Stimulated Planning since players have to consider which Agents or Traps can detect them from all locations that need to be entered. The same applies to ways of succeeding with Reconnaissance goals.

The presence of Line of Sight rules in a game are likely to affect how important it is to have Area Control of various parts of Game Worlds.


Can Instantiate

Alignment, Fog of War, Spatial Engrossment

with Stealth

Stimulated Planning

Can Modulate

Agents, Aim & Shoot, Area Control, Automated Responses, Avatars, Combat, Evade, Focus Loci, Game World Navigation, Game Worlds, Landmarks, Levels, Movement, Reconnaissance, Sniper Locations, Stealth, Strongholds, Traps, Units

Can Be Instantiated By

Aim & Shoot, Big Dumb Objects, First-Person Views

Can Be Modulated By

Avatars, Diegetically Tangible Game Items, Environmental Effects, Obstacles, Privileged Abilities, Units, Vision Modes

Possible Closure Effects

Potentially Conflicting With


New pattern created in this wiki.