Alien Aggression (LWR)
In General
The more XCOM performs activities that harass the alien entity, the higher the alien's Aggression will become. Aggression determines which kinds of missions the aliens will run each month, if the aliens should increase their leader levels, and if they aliens should redirect their Harvest missions.
Increasing and Decreasing Aggression
Aggression is a value between 0 and 100% that moves up during the month and decreases at the beginning of each new month. It can only ever be 5 values: 0%, 25%, 50%, 75%, or 100%.
Increasing Aggression
A running tally of aggression is incremented over the course of the month as XCOM successfully launches operations against alien UFOs.
Destroy or successfully assault a Scout, Fighter: +25 (25% chance) Destroy or successfully assault a Raider, Destroyer, or Abductor: +25 (50% chance) Destroy or successfully assault a Harvester, Terror Ship, Transport: +25 (100% chance) Destroy or successfully assault a Battleship, Assault Carrier, or Overseer: +50 (100% chance) Perform a Combat Patrol: +25 (100% chance)
Decreasing Aggression
At the beginning of each month, aggression is reduced by 25% if it was 25% or 50% and it is reduced by 50% if it was 75% or 100%.
However, if an Alien Base was raided in the last month, the Aggression is set to 100% instead.
Effect of Aggression
Aggression is intended to reflect the alien's becoming more aware of XCOM and XCOM becoming more threatening to them.
Alien Missions
Aggression is used to determine the types of missions the aliens will field.
In general, High Aggression leads to:
Triggering an XCOM Base Defense Mission
More Hunt Missions More Research Missions More Bombing Missions More Terror Missions
Less Infiltrations Less Abductions Less Harvest Missions
Alien Leaders
0-74% Aggression: Normal levels on alien leaders 75-99% Aggression: +1 Level to all alien leaders 100% Aggression: +2 Levels to all alien leaders
Protecting Harvesters
If the aliens are being very aggressive, they will try to move their Harvest Missions that reside in XCOM territory. This will cost them 2% resource each time they do, and they may have to do this multiple times.
Relocate chance: Aggression / 2