Alien Aggression (LWR)
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 and down throughout a campaign.
Aggression is incremented as XCOM destroys or successfully assaults alien UFOs:
|Ship Destroyed or Successfully Assaulted||Aggression (modified by Campaign Length)|
|Scout or Fighter||25% chance for +12.5%|
|Raider or Destroyer||50% chance for +12.5%|
|Harvester, Terror Ship, Transport, or Abductor||+12.5%|
|Battleship, Assault Carrier, or Overseer||+25%|
It is also increased when XCOM launches Combat Patrols or successfully raids an Alien Base:
|Successful Alien Base Assault||+100%|
|Beginning of Month after a Successful Alien Base Assault||Set to at least 50%|
Aggression is reduced throughout the game as time passes (checked every 30 minutes) in intervals of 12.5%.
The chance of reduction is proportional to how much aggression the aliens have (i.e. 100% aggression decreases twice as fast as 50% aggression).
Effect of Aggression
Aggression is intended to reflect the alien's becoming more aware of XCOM and XCOM becoming more threatening to them.
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
75% Aggression: +1 Level to all alien leaders 100% Aggression: +2 Levels to all alien leaders
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