Fog of War

Hiding information about parts of game worlds that are not being observed or have not yet been explored by players.

This pattern is a still a stub.

Many strategy games hide information about areas at the beginning of the game, typically marking these areas as grayed out or otherwise covered. As all players are subject to this lack of information they may do actions which would otherwise be bad tactical moves, in one way simulating Fog of Wars of older battlefields. As having knowledge of the surroundings is a tactical advantage, the unexplored areas encourage exploration and to further support this, the edges of the unknown areas often reveal some information, for example having the areas "fogging out" around the edges.

Fog of War is typically used in an additional way besides hiding the terrain. Even if the areas have been explored, the movement of enemy units through those areas is typically not shown unless under the observation of a player's own units.

Examples

The Civilization series of computer games lets the players start with just the areas around his or her starting units explored. The choice between whether to put resources into improving ones cities or exploring the environment, make up a large portion of success or failure in the game.

Upgrades provide further vision range

Metroid Fusion reveals most of the layout of each level and even explicitly indicates the places the player has already visited. The game further indicates the location of the power-ups on the overview map, but not the exact location on the play area. This leads to the player, sometimes frantically, trying to find the exact location of the power-up in the specified area.

Using the pattern

Two main design choices exist for Fog of War: is the Fog of War shared by all players and does the Fog of War return after players have explored an area? The second design choice can be modulated further by differentiating between a Fog of War that hides the Game World and a Fog of War that does not hide the Game World but does hide game elements in it. Regardless, when the Fog of War returns to an explored area it promotes Memorizing the contents of the areas.

Fog of War relies on the movement and observation ranges of Avatars or Units to explore unknown areas. This provides the game designer with opportunities to provide different levels of proficiency for different Units, giving them Privileged Abilities or Asymmetric Abilities and creating Orthogonal Unit Differentiation. For example, in the real-time strategy game WarCraft II players can choose to build very strong attack units which have limited capabilities for gaining information about the enemy units they encounter. This is an example of applying the Trade-Offs pattern between making Gain Information or Eliminate goals easier, although the actual balance is not easy to judge. One way of creating Fog of War is to use Tile-Laying and having the Tiles upside down until they have been explored. However, this makes the Fog of War common to all players.

Games with Game State Overview typically apply the use of Fog of War at the same level as for the game world. The most common exception can be found in games using Third-Person View. Such games may let players have full view of the area currently visited, in essence having no Fog of War in the Game World view but having one in the Game State Overview which is updated as different parts of the Game World are explored.

Can Be Instantiated By

Avatars, Line of Sight, Tile-Laying

Can Be Modulated By

Privileged Abilities

Consequences

Fog of War modulates players' perception of Game Worlds. It provides means of giving Imperfect Information in games with Third-Person or God Views comparable to that which comes automatically in games with First-Person Views. It can modulate God Fingers so that one has the freedom to fully move over entire Game Worlds but without revealing all information within them. In games with Reconfigurable Game Worlds, Fog of War can require players to engage in Memorizing.

Since knowing the terrain of Game Worlds and what it contains most often gives tactical advantages, the presence of Fog of War naturally creates Gain Information and, more specifically, Game World Exploration goals. When Fog of War comes in two layers, making a difference between what has not been seen at all and that which currently is not seen, the pattern also modulates Game World Exploration since it encourages players to repeatedly explore the same areas to notice difference. When this becomes a more structure gameplay activity, it is in fact a Guard or Reconnaissance goal. Needing to consider Fog of War in these ways affect how players can and need to do Stimulated and Tactical Planning.

Fog of War can modulate many types of actions through introducing Imperfect Information, but this is probably most directly noticeable in games with Combat.

Relations

Can Instantiate

Game World Exploration, Imperfect Information

with Reconfigurable Game Worlds

Memorizing

Can Modulate

Combat, Game World Exploration, Game Worlds, God Fingers, God Views, Mini-maps, Stimulated Planning, Tactical Planning, Third-Person Views

Can Be Instantiated By

Avatars, Line of Sight, Tile-Laying

Can Be Modulated By

Privileged Abilities

Possible Closure Effects

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Potentially Conflicting With

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History

An updated version of the pattern Fog of War that was part of the original collection in the book Patterns in Game Design.