An Explorer's Line of Sight
Line of Sight, often abbreviated to LOS, is a gameplay element in most strategy games. LOS refers to the vision an object is granting to its owner (and often allies, spectators, rarely enemies) over its surrounding area uncovering Fog of War and is represented by a number showing the distance of uncovering.
As units move, are created, and buildings are built the fog of war around them is cleared away, while the absence or death of a unit resolves in the fog of war recovering the area. Since units and buildings differ in their LOS some are better for the purpose of scouting than others and most games feature units that are specifically focused on the role of scouting.
Concept of LOS
While traditional board games provide perfect information to all participants, RTS games use the Fog of War and LOS to keep one players movements and decisions secret from the others unless scouted. Thus every player has his own field of LOS 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 LOS.
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 not only from opponents, but initially from all players. 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 LOS are ranged units. While they themselves in the Age of Empires series have LOS 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 LOS. For a short amount of time they are added to the victims players LOS to show where exactly ranged attacks came from.
Upgrades
LOS can be upgraded with the following technologies:
Age of Empires II
- Cartography grants LOS over allied players which is not available by default. It is free for the Portuguese. They and their team members see each other's LOS from the game start.
- Town Watch +4 building LOS
- Town Patrol +4 building LOS
- Tracking +2 infantry LOS
All upgrades that increase range also increase the LOS.
Age of Mythology
God powers
- Spy grants LOS over an enemy unit.
- Vision grants LOS over a large area for twenty seconds.
- God powers like Meteor and Locust Swarm grant LOS over the affected area.
- God powers like Plague of Serpents, Ancestors, Fimbulwinter, Nidhogg, Walking Woods, Sentinel, Carnivora, and Tartarian Gate create units providing LOS.
- Most god powers capable of damaging the opponent directly require the caster to have LOS in the target area.
Common technologies
- Signal Fires (+6 building LOS)
- Carrier Pigeons (+6 building LOS)
- Line upgrades like Medium Infantry add LOS 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 LOS to walls.
- Relic Pelt of Argus + LOS for units
- Relic Harter's Folly + LOS for scouts
- Relic Head of Orpheus + LOS for buildings
- Relic Trios' Bow + LOS and range for archers
- Omniscience grants LOS over all players on the map. It's 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.
Greek technologies
- Lord of Horses (+4 LOS to cavalry)
- Winged Messenger (Pegasi + 6 LOS)
- Oracle (+6 LOS to all units, +8 LOS to all buildings)
Egyptian technologies
- Egyptian Pharaohs gain automatically 6 LOS in the Heroic Age and 2 LOS in the Mythic Age.
- Egyptian Priests gain automatically 8 LOS in the Classical Age, 6 LOS in the Heroic Age and 2 LOS in the Mythic Age.
- Hands of the Pharaoh (+2 LOS and range for Priests)
- Crocodopolis (Petsuchos + 4 LOS and range)
Norse technologies
- Eyes in the Forest (+3 LOS to infantry)
Atlantean technologies
- Focus (Atlantean Oracle LOS gaining takes -1 second)
- Lemurian Descendants (+9 LOS to all human units)
- Eyes of Atlas (+9 LOS to all myth units)
- Io Guardian (+5 LOS to Argus)
Age of Empires III
- Town Watch (+2 LOS to units)
- Gas Lighting (+4 LOS to buildings)
- TEAM Inquisition (Spanish, +10 LOS to all units)
- TEAM Cavalry Scouts (Russians, +4 LOS to cavalry)
- TEAM Infantry Scouts (Iroquois, +8 LOS to infantry)
- Bakufu (Japanese, +20 to Daimyo and Shogun LOS)
- (Advanced) Hot Air Balloon (Summons a unique scout unit with a LOS of 38.)
Trivia
Age of Mythology
- Classical Age cavalry provides very little LOS. Both the Greek Hippikon and the Norse Raiding Cavalry grant only 8 LOS while Villagers provide 14, infantry 16, and ranged units even more LOS. Since the LOS value is a radius around the unit the area covered by LOS 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.