Line of Sight

Line of Sight, often abbreviated to LOS, is a gameplay element in most strategy games.

Overview
The Line of Sight of a unit or building is the clearly visible area around it, in which any enemy units and buildings are visible. As units move and buildings are built, the black (unexplored) areas or fog of war are cleared away. Different units and buildings have different LOS, and most games feature units that are specifically focused on the role of scouting.

Knowledge is power and LOS can be a very powerful weapon if used properly. Those who ignore scouting during gameplay may usually find themselves an easy target for the opposition. Scouting also requires rescouting, so players can always be kept to date on the latest enemy movements.

Upgrades
LOS can be upgraded with the following technologies:

Age of Empires II

 * Town Watch +4 building LOS
 * Town Patrol +4 building LOS
 * Tracking +2 infantry LOS

Age of Mythology

 * Signal Fires (+6 building LOS)
 * Carrier Pigeons (+6 building LOS)
 * Lord of the Horses (+4 LOS to cavalry)
 * Oracle (+6 LOS to all units and buildings)
 * Eyes in the Forest (+3 LOS to infantry)
 * Lemurian Descendants (+9 LOS to all human units)
 * Eyes of Atlas (+9 LOS to all myth units)
 * Io Guardian (+5 LOS to Argus)
 * Focus (Atlantean Oracle LOS gaining takes -1 second)
 * Crocodopolis (Petsuchos + 4 LOS and range)
 * Winged Messenger (Pegasi + 6 LOS)
 * 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
 * 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 updates.
 * 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)

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 (Japan, +20 to Daimyo and Shogun LOS)
 * Hot Air Balloon &amp; Advanced Hot Air Balloon (Summons a unique scout unit with a LOS of 38.)