Line of Sight

A preview image of an Explorer's Line of Sight from Age of Empires III: Definitive Edition.

Line of Sight, often abbreviated to LOS, is a gameplay element in most strategy games. Line of Sight refers to the vision an object grants to its owner (and often allies and spectators, but rarely enemies) over the surrounding area, uncovering the Fog of War.

As both buildings and units are created, with the latter moving, the fog of war around them is cleared away. The death of a unit results in the fog of war recovering the area. Since units and buildings differ in their Line of Sight numbers, some are better for scouting than others and most Age of Empires games feature units that specialize in scouting.

Concept

While traditional board games provide perfect information to all participants, real-time strategy (RTS) games use the fog of war and Line of Sight to keep one players movements and decisions secret from the others unless scouted. Thus every player has their own field of Line of Sight which in general differs from that of other players while such fields are allowed to overlap each other. Areas of conflict are always inside of overlapping Line of Sight.

RTS games like Starcraft only hide information from opponents in a grey shroud while revealing knowledge of the map setup to all players. The Age of Empires series goes one step further. Maps are generated randomly and hide information from all players initially. Thus besides of the observation of the map initial exploration is required as well.

Fog of War

Removing the black fog is important to find the resources on which to rely once the player runs out of the starting resources, as well as to learn about the map setup for territorial ambitions and to find the enemies and sometimes even allies on the map, whereas removing the grey shroud is required to keep track of the other players actions and thus control over certain areas.

An exception to the rule of Line of Sight are ranged units. While they themselves in the Age of Empires series have Line of Sight matching or surpassing their range, other players will spot them when being hit by such ranged units even if the ranged units should be out of Line of Sight. For a short amount of time they are added to the victims players Line of Sight to show where exactly ranged attacks came from.

Age of Empires II

In Age of Empires II, Cartography allowed players to share Line of Sight of allies. With patch 5.7, it was removed from the game as a technology and its effects granted automatically upon construction of a Market. With update 73855, Cartography effects now apply at the start of the game on standard settings, thus making players share their ally's Line of Sight from the start of the game.

Buildings

Units	Base LOS	Max. LOS
Castle	11	20
Outpost	12	20
Watch Tower, Guard Tower, Keep, Harbor, Krepost, Donjon	10	20

Upgrades and bonuses

All upgrades that increase range also increase the Line of Sight by the same amount (but not vice versa). As such, the section is further divided. Unless mentioned otherwise, the technology is generic.

Line of Sight upgrades only

• All infantry units receive +2 Line of Sight upon advancing to the Feudal Age.
• Eagle Scout receive another +1 (for a total of +3) Line of Sight upon advancing to the Feudal Age.
• Scout Cavalry line and Outposts receive +2 Line of Sight upon advancing to the next Age every time.
• Fletching, Bodkin Arrow and Bracer give +1 Line for Sight to Town Centers.
• Siege Engineers gives +1 Line of Sight for Siege Tower and Battering Ram line.
• Town Watch and Town Patrol give +4 Line of Sight for buildings, except Farms, Fish Traps, walls and gates.
• Spies allows the player to see the enemy's Line of Sight. Treason reveals all enemy Kings for a short time.
• Armenians: Infantry have +2 Line of Sight (team bonus).
• Burmese: Relics are visible on the map from the game start (team bonus).
• Chinese: Town Center has +7 Line of Sight.
• Ethiopians: Outposts have +3 Line of Sight (team bonus).
• Franks: Knight line units have +2 Line of Sight (team bonus).
• Japanese: Galley line units have a +50% longer Line of Sight (team bonus).
• Koreans: Villagers have +3 Line of Sight.
• Malay: Docks have double Line of Sight (team bonus).
• Mongols: Scout Cavalry line has +2 Line of Sight (team bonus).
• Sicilians: Transport Ships have +5 Line of Sight (team bonus).
• Tatars: Mounted archers have +2 Line of Sight (team bonus).
• Vietnamese: Enemy positions are visible at game start.

Range upgrades

• Fletching, Bodkin Arrow and Bracer give +1 Line of Sight for Archer, Cavalry Archer, Skirmisher, and Galley lines, and most unique archers and ships. They also give +1 Line of Sight to defensive structures.
• Block Printing gives +3 Line of Sight for Monks and Missionaries.
• Siege Engineers gives +1 Line of Sight for all ranged siege units.
• Aztecs: Atlatl unique technology gives +1 Line of Sight for Skirmisher line and Genitours.
• Armenians: Cilician Fleet gives +1 Line of Sight for the Galley line and Dromons.
• Britons: Yeomen unique technology gives +1 Line of Sight for foot archers. Foot archers (except Skirmishers) have +1/+2 Line of Sight in the Castle/Imperial Age.
• Byzantines: Greek Fire unique technology gives +1 Line of Sight for Fire Galley line.
• Franks: Bearded Axe unique technology gives +1 Line of Sight for Throwing Axeman.
• Hindustanis: Shatagni unique technology gives +2 Line of Sight for Hand Cannoneers.
• Khmer: Scorpions have +1 Line of Sight (team bonus).
• Koreans: Eupseong unique technology gives +2 Line of Sight for Watch Tower line. Shinkichon unique technology gives +1 Line of Sight for Mangonel line.
• Lithuanians: Hill Forts unique technology gives +3 Line of Sight for Town Center.
• Magyars: Recurve Bow unique technology gives +1 Line of Sight for Cavalry Archer line.
• Tatars: Timurid Siegecraft unique technology may give +1 Line of Sight for Trebuchet.
• Teutons: Crenellations unique technology gives +3 Line of Sight for Castle.
• Turks: Artillery unique technology gives +2 Line of Sight for Bombard Cannon, Cannon Galleon, and Bombard Tower.

Trivia

• Despite Siege Engineers increasing range for ranged siege units only, it also gives +1 Line of Sight to the ram line and the Siege Tower.
• For most units with range, their Line of Sight is simply $Range + 2$. For all other remaining units, it is $Range + 3$. The Fire Galley line is the only exception having $Range + 3.5$ Line of Sight.
• Line of Sight for units and buildings is capped at 20 tiles so further bonuses or technologies cannot provide more.
• "marco" and "polo" cheat codes can be used to reveal map and remove fog of war respectively. The cheat code "natural wonders" grants the line of sight of gaia.

Age of Mythology

God powers

• Spy grants Line of Sight over an enemy unit.
• Vision grants Line of Sight over a large area for twenty seconds.
• God powers like Meteor and Locust Swarm grant Line of Sight over the affected area.
• God powers like Plague of Serpents, Ancestors, Fimbulwinter, Nidhogg, Walking Woods, Sentinel, Carnivora, and Tartarian Gate create units providing Line of Sight.
• Most god powers capable of damaging the opponent directly require the caster to have Line of Sight in the target area.

Technologies

Common

• Signal Fires (+6 building Line of Sight)
• Carrier Pigeons (+6 building Line of Sight)
• Line upgrades like Medium Infantry add Line of Sight to units as well. They are available for all human units and are divided into Medium in the Classical Age, Heavy in the Heroic Age, and Champion in the Mythic Age. Units available in later Ages might miss out on the first line upgrades.
• Wall line upgrades like Stone Wall may also provide + 2 Line of Sight to walls.
• Relic Pelt of Argus + 6 Line of Sight for units
• Relic Harter's Folly + 2 Line of Sight for scouts
• Relic Head of Orpheus + 8 Line of Sight for buildings
• Relic Trios' Bow + 2 Line of Sight and range for archers
• Omniscience grants Line of Sight over all players on the map. Its price depends on the amount of hostile units and is only affordable in the very late game or when one of the players is facing defeat and should already have resigned. Thus it helps the winning players to avoid searching the whole map and ending the game.

Greeks

• Lord of Horses (+4 Line of Sight to cavalry)
• Winged Messenger (Pegasi + 6 Line of Sight)
• Oracle (+6 Line of Sight to all units, +8 Line of Sight to all buildings)

Egyptians

• Egyptian Pharaohs gain automatically 6 Line of Sight in the Heroic Age and 2 Line of Sight in the Mythic Age.
• Egyptian Priests gain automatically 8 Line of Sight in the Classical Age, 6 Line of Sight in the Heroic Age and 2 Line of Sight in the Mythic Age.
• Hands of the Pharaoh (+2 Line of Sight and range for Priests)
• Crocodopolis (Petsuchos + 4 Line of Sight and range)

Norse

• Eyes in the Forest (+3 Line of Sight to infantry)

Atlanteans

• Focus (Atlantean Oracle Line of Sight gaining takes -1 second)
• Lemurian Descendants (+9 Line of Sight to all human units)
• Eyes of Atlas (+9 Line of Sight to all myth units)
• Io Guardian (+5 Line of Sight to Argus)

Trivia

• Classical Age cavalry provide very little Line of Sight. Both the Greek Hippikon and the Norse Raiding Cavalry grant only 8 Line of Sight while Villagers provide 14, infantry 16, and ranged units even more Line of Sight. Since the Line of Sight value is a radius around the unit, the area covered by Line of Sight greatly differs with only small changes in numbers. This makes it more difficult to raid the enemy with cavalry early on.
• The player can check if an opponent is taking an explored but currently not observed Settlement by trying to build one oneself. If the player is not allowed to, another player is already building it.
• Another exploit is the selecting of explored but currently not observed huntables. If the HP bar is not shown, the animals are already dead and likely to be hunted right now or already have been hunted.
• Egyptian Priests and Fishing Ships can create Obelisks, which provide moderate Line of Sight. The Egyptians can also construct the Lighthouse in the Mythic Age, which provides a gigantic Line of Sight.

Age of Empires III

Technologies

• Town Watch (+2 Line of Sight to units)
• Gas Lighting (+4 Line of Sight to buildings)
• Ranged Cavalry Caracole (+2 Line of Sight to ranged light cavalry and +1 Line of Sight to ranged heavy cavalry)
• Gunner's Quadrant (+6 Line of Sight to artillery)
• Ottoman Consulate (Indians, +10 Line of Sight to all units)
• Disciplined Gurkha, Honored Gurkha, Exalted Gurkha (Indians, +1 Line of Sight to Gurkhas)
• Veteran Abus Gunners, Guard Abus Gunners (Ottomans, +1 Line of Sight to Abus Gunners)
• Infantry Guns, Imperial Infantry Guns (Swedes, +1 Line of Sight to Leather Cannons)
• Lacrosse (Haudenosaunee, +2 Line of Sight to Aennas, Forest Prowlers and Tomahawks)
• Chincha Rafts gain +2 Line of Sight upon reaching Fortress Age and Industrial Age (Inca)
• Sebastopol Mortars gain +6 Line of Sight upon reaching Industrial Age and Imperial Age (Ethiopians)
• Somali Lighthouses (+10 Line of Sight to Outposts, Docks, Ports, Trading Posts, Blockhouses, War Huts, Castles, Fixed Guns, and Watch Towers)
• Army of the Pure (+2 Line of Sight to Chakram Throwers)

Home City cards

• Agents ((British, Dutch, Germans, Portuguese, United States), +15 Line of Sight to Spies)
• Offshore Support ((British, Ottomans, Aztecs, Incas, Italians, Maltese), +2 Line of Sight to warships)
• European Cannons ((Indians, Japanese, Chinese, Ethiopians, Hausa, Mexicans), +2 Line of Sight to warships)
• Armada (Spanish, +2 Line of Sight to warships)
• Grenade Launchers, Washington's Legion (+2 Line of Sight to Grenadiers)
• Yeomen (British, +4 Line of Sight to Longbowmen)
• Temple of Tlaloc Support (Aztecs, +4 Line of Sight to Eagle Runner Knights)
• Way of the Bow (Japanese, +2 Line of Sight to Yumi Archers)
• Rangefinding (Portuguese, +8 Line of Sight to Mortars)
• Genitours (Portuguese, +4 Line of Sight to Dragoons)
• Morutaru Range (Japanese, +4 Line of Sight to Morutarus)
• Stone Towers (Aztecs, +6 Line of Sight to War Huts and Nobles' Huts)
• Yamashiro (Japanese, +6 Line of Sight to Castles)
• Bakufu (Japanese, +20 Line of Sight to Daimyo and Shogun)
• High Ground (Incas, +15 Line of Sight to War Huts, Town Centers, Tambos and Strongholds)
• Snaplock (Swedes, +3 Line of Sight to Caroleans and +1 Line of Sight to Hakkapelits)
• Long Rifles (United States, +4 Line of Sight to State Militia and Minuteman)
• Mississippi Steamers (United States, +2 Line of Sight to Steamers)
• Massina Madrasahs (Hausa, +10 Line of Sight to Universities)
• Refurbished Firearms (Mexicans, +2 Line of Sight to Soldados)
• Steel Bolts ((Italians, Maltese), +2 Line of Sight to Pavisiers/Crossbowmen)
• Dignitaries (Maltese, +4 Line of Sight to Hospitallers)
• Flintlock Rockets (Maltese, +2 Line of Sight to Sentinels)
• (Advanced) Hot Air Balloon (Summons a unique scout unit with a Line of Sight of 38)
• TEAM Inquisition (Spanish, +10 Line of Sight to all units)
• TEAM Cavalry Scouts (Russians, +4 Line of Sight to cavalry)
• TEAM Infantry Scouts (Haudenosaunee, +8 Line of Sight to infantry)
• TEAM Ranged Cavalry Combat (Swedes, +1 Line of Sight to all ranged cavalry)

Advancing in age also grants a Line of Sight upgrade to buildings :

Age	Line of Sight bonus
	7
	4
	4
	4

Gallery

An Explorer's Line of Sight in Age of Empires III.

A Monk's very long Line of Sight and a Cow's short Line of Sight, in Age of Empires II.

See also

• Scout unit