Fog of War in Video Games Explained: From Tabletop Wargames to Modern Shooters

Fog of war in video games is the design technique that hides parts of the map or world from the player until a unit, character, or sensor reveals them. It is one of the oldest tricks in interactive design, older than the home console, older than the personal computer, older even than the digital game itself. Yet it is still everywhere, from chess variants to soulslike level design, from real-time strategy classics to battle royales played by millions every weekend.

The reason it has survived is simple. Limited information makes decisions interesting. When you cannot see the whole board, you have to guess, scout, commit, regret, adapt. That loop is the engine of strategy, horror, exploration, and multiplayer tension. This guide walks through where fog of war came from, the different flavors designers actually ship, how the math works under the hood, and why the technique keeps mutating to fit new genres.

Table of Contents

• Origins: Kriegsspiel and the Prussian Wargame
• The Three Types of Fog of War
• RTS Fog of War: Dune II, Warcraft, StarCraft
• How Fog of War Works Under the Hood
• Fog of War in Horror and Exploration
• Fog of War in Modern Multiplayer
• Why Designers Keep Coming Back to It
• FAQ

Origins: Kriegsspiel and the Prussian Wargame

The phrase “fog of war” predates video games by more than a century. It comes from the Prussian military theorist Carl von Clausewitz, who wrote in the 1830s about the uncertainty that clouds every battlefield decision. Generals never have complete information. They guess based on scouts, dust clouds, the noise of artillery on the next ridge.

Prussian officers turned that idea into a teaching tool called Kriegsspiel, German for “wargame.” The game used a referee who held the full map, and two players who each saw only what their units could plausibly observe. If a cavalry detachment rode behind a hill, the opposing player simply did not know it was there until contact. This was, mechanically, the first fog of war system. It existed in the 1820s, played with wooden blocks and a paper map.

Tabletop wargaming carried the idea forward through the 20th century. Hidden movement, double-blind setups, hidden bases, all of these are Kriegsspiel descendants. When computer games arrived, designers inherited the convention without needing to invent it. The screen was already a partial view of the world. Hiding the rest was a small jump.

The Three Types of Fog of War

Modern fog of war in video games breaks into three distinct categories. Most games use a mix.

Unexplored Black

The map starts entirely black. Areas you have not visited stay invisible. You see nothing about terrain, resources, or enemies until a unit physically walks there. This is the harshest form. Dune II, often credited as the first commercial RTS to popularize fog of war, used this style in 1992. It rewards scouting and punishes blind expansion.

Explored But Dimmed (True Fog)

Once you have explored an area, the terrain stays visible on your map, but enemy units inside it become hidden again as soon as your own units leave. You remember the geography, you do not remember what is moving through it. StarCraft, Age of Empires, and Civilization all use this style. It is the closest digital analogue to how a real commander would actually think about a battlefield. Roads stay where they are, the enemy army does not.

Line of Sight and Sensor Cones

In shooters, stealth games, and modern tactical titles, fog of war becomes a per-character line of sight calculation. Metal Gear Solid uses sight cones for guards. XCOM hides enemies until your soldier sees them. Counter-Strike has no minimap fog technically, but the inability to see through walls is the same principle scaled down to one player and one room.

RTS Fog of War: Dune II, Warcraft, StarCraft

The real-time strategy genre is where fog of war became a discipline. Westwood Studios put true fog into Dune II in 1992. Blizzard refined the system in Warcraft: Orcs and Humans in 1994, then again in Warcraft II with proper terrain memory. By the time StarCraft launched in 1998, the implementation was fully mature.

StarCraft made fog of war a competitive mechanic. Scouting was not optional, it was a tax you paid every minute of the game. A Terran player who did not scan with a Comsat could lose to a hidden Lurker rush. A Protoss player who missed a Mutalisk swap died in seconds. The map was a chessboard where half the pieces were invisible and the visible half lied. Korean professional StarCraft, with its 20-year competitive history, can be read as a long argument about fog of war management.

This DNA is still everywhere. Total War games use line of sight with terrain elevation. Company of Heroes adds shot-blocking foliage. Even games with procedurally generated maps usually pair the generation with some form of progressive reveal, because handing the player a full map of a random world erases most of the discovery.

How Fog of War Works Under the Hood

Under the hood, classic RTS fog is a grid. The map is divided into cells, often the same grid used for pathfinding. Each cell has a visibility state per player. The three common states are unexplored, explored but not currently visible, and currently visible.

Every frame, the engine asks each unit: which cells are inside your sight radius? It writes “currently visible” to those cells for that player. Cells that were visible last frame but not this frame get demoted to “explored but not visible.” Cells that were never visible stay unexplored.

The render layer then draws the map in three passes. Unexplored cells get a solid black overlay. Explored cells get a darker tint and show terrain but freeze unit positions to whatever was last seen. Currently visible cells render with full information including enemy units.

Modern engines add tricks. Sight cones for stealth games use raycasting against geometry. Shooters use full 3D occlusion through BSP trees or portal culling, which is technically a rendering optimization but doubles as fog of war because anything behind a wall is genuinely not drawn. Tile-based tactics games like XCOM use voxel-based field of view with cover bonuses. The fundamentals stay the same. Some authoritative source decides what each viewer can see, then hides everything else.

The interesting wrinkle is that fog of war is a server-authoritative system in any competitive multiplayer game. The client must never know more than it is allowed to display, otherwise wallhack cheats and map hacks become trivial. This is why anti-cheat in games like Counter-Strike spends so much effort on detecting clients that have modified the renderer to draw through fog. If the data is on the client, it can be read. Real fog of war ships nothing to clients they should not see.

Fog of War in Horror and Exploration

Horror games discovered fog of war from a different angle. Silent Hill in 1999 used literal fog as both atmosphere and a draw distance trick on the original PlayStation. The hardware could not render the whole town, so Konami wrapped the limitation in story. The fog became a character. You could not see ten meters in front of you, and the radio crackled when something you could not see was already too close.

This is fog of war as dread. The player has full positional control but minimal information. Resident Evil camera angles do something similar. The fixed cinematic shots hide what is around the corner, turning every door into a guess.

Exploration games inherited the same idea. Subnautica hides everything below visual range with literal underwater fog. Outer Wilds maps fill in only as you find them. Roguelikes like the classic ASCII dungeon crawlers revealed dungeon floors tile by tile as your character stepped, which is a direct port of Kriegsspiel logic to a single-player permadeath context.

The claustrophobic horror game Iron Lung is fog of war taken to its limit. The player has no window. You navigate a submarine by sonar pings, drawing a mental map on paper as you go. The entire game is the fog. The reveal is the horror.

Fog of War in Modern Multiplayer

Battle royale games are fog of war scaled to 100 players on a giant map. You see what your character sees, you hear what your character hears, and you guess the rest. The shrinking circle is a fog of war pressure mechanic. It forces revelation. Players who hid in a corner have to leave it, and the corner they run to was a different player’s hidden corner ten seconds ago.

MOBAs took the RTS model and stripped it down. League of Legends and Dota 2 use unit-based vision with wards, which are little scouting beacons players buy and place to extend the map. Ward placement is a meta-game inside the game. A well-warded jungle is a known jungle. An unwarded jungle is a death trap. Professional MOBA play is largely an information war.

Asymmetric horror games like Dead by Daylight invert fog of war between roles. The killer sees the survivors via heartbeats and aura reveals. The survivors hear the killer but cannot see them outside a radius. Two players in the same room can have completely different views of the same scene. That information asymmetry is the entire design.

Why Designers Keep Coming Back to It

Fog of war works because human brains are pattern-completing machines. Show a player a partial picture and they will fill in the rest, usually with something worse than the truth. A black tile on a strategy map could contain anything. The mind picks the scariest possibility and plans around it. That free narrative production is impossible to buy with art assets alone.

It also creates meaningful decisions. A game with full information is solvable in principle. Chess is hard because the search tree is huge, not because the position is hidden. Add fog of war to chess and you get something fundamentally different, a game where bluffing, deduction, and risk management matter as much as raw calculation. This is why speedrun categories often distinguish runs that exploit perfect knowledge of hidden content from runs that play blind. The hidden information is a real resource. Knowing what is behind the fog is a different game from not knowing.

The technique also scales beautifully. A two-player tabletop wargame and a 100-player battle royale use the same core principle. The implementation differs, but the design idea is identical. That is rare in game design, where most techniques are genre-specific. Fog of war is genre-agnostic, which is why it keeps showing up in everything from metroidvania map systems to grand strategy games to mobile puzzle titles.

FAQ

What is fog of war in video games?

Fog of war is a design system that hides parts of the map or world from the player until something owned by the player reveals them. It can mean a black overlay on unexplored areas, dimmed terrain you have seen but cannot currently observe, or per-character line of sight cones in 3D games.

What was the first video game with fog of war?

The technique appeared in early tabletop wargames in the 1820s and migrated to computers through the late 1970s and 1980s. Empire (1977) is often cited as an early digital example. Dune II in 1992 popularized the term and the visual convention for real-time strategy.

Why do RTS games use fog of war?

It forces scouting and rewards information management. Without fog of war, both players see the whole map at all times and combat becomes pure optimization. With fog of war, you have to spend resources to learn what your opponent is doing, and your opponent can deceive you.

Is fog of war just a graphical effect?

No. The graphical overlay is the surface. Underneath, the game engine tracks visibility per player per cell or per object. In competitive multiplayer the server actually withholds data from the client, which is why proper fog of war is a security feature as well as a design choice.

What is the difference between fog of war and line of sight?

Line of sight is the per-character calculation of what a unit can see right now. Fog of war is the broader system that combines line of sight with map memory, exploration state, and information persistence. Line of sight is the input. Fog of war is the output the player sees.

Conclusion

Fog of war is one of those rare design techniques that solves three problems at once. It generates strategic depth by forcing decisions under uncertainty. It generates emotional tension by letting the player’s imagination fill the gaps. It generates technical headroom by giving engines an excuse to render less. Two hundred years after Prussian officers pushed wooden blocks across paper maps, the same idea drives most of the multiplayer games being played right now. The fog is not going anywhere.