This is a brief introduction to AI scripting in Age Of Empires II. In the following resources you may find an in depth overview of the tools and relevant settings.

Resources:

• interlepus YouTube Playlist (English)
• arandi YouTube Playlist (English)
• AI Game Junction YouTube Playlist (English)
• Igor Hernández YouTube Playlist (Spanish)
• UserPatch AI Scripters
• AoK Heaven Games - World of AI Scripting Chapter 1
• Microsoft’s Computer Player Strategy Builder Guide Documentation
• AI Scripting Encyclopedia by airef
• AI Scripters Discord Link

.per and .ai files:

• AIs files come in pairs: name.ai and name.per (name’s must be identical).
• This files should be located:

— AoE II DE: C:\Program Files (x86)\Steam\steamapps\common\AoE2DE\resources\_common\ai\

— Classic AoE II: \Age Of Empires II\AOE II - The Conquerors\AI

Scripting Language Overview:

• AoE II scripting language is based on CLIPS (C Language Integrated Production System).
• Defining rules involves defrule instruction with facts and actions.
• Facts trigger actions as long as they remain true unless disabled.
• Example:

(defrule
	(true)
=>
	(chat-to-all "Hi, let's play AoE II!")
	(disable-self)	;Disable after executed once.
)

Programming Levels:

• There are five levels of AoE II programming:
  1. Defrules, defconsts, timers…
  2. Random generator, conditional (file) loading, goals
  3. Strategic Numbers
  4. Userpatch commands
  5. Direct Unit Control

Scouting the Map:

• Level 3 programming involves strategic numbers (SN) for adjusting AI parameters.
• SN adjust AI behavior and can be changed throughout the game.
• Default values are important to understand AI behavior fully.

Setting Strategic Numbers:

(defrule
	(true)
=>
	(set-strategic-number strategic-number number)
	(disable-self)
)

Example:

(defrule
	(true)
=>
	(set-strategic-number sn-cap-civilian-explorers 0)
	(set-strategic-number sn-total-number-explorers 0)
	(disable-self)
)

Units and Buildings IDs:

• IDs list: Unit/Building ID list
• Define constants using (defconst constant-name constant-value).

Example:

(defconst livestock-class 958)
(unit-type-count livestock-class > 0)

Conditionals:

• Use #load-if-defined to check civilization.
• Example:

#load-if-defined BRITON-CIV
	(defconst text-my-civ "I'm Britons, will make Longbows")
#else
	(defconst text-my-civ "I'm not Britons, will not make Longbows")
#end-if

Training Villagers:

• Use fact-checkers like can-train to avoid bugs.
• Example:

(defrule
	(can-train villager)
=>
	(train villager)
)

Miscellaneous:

• Use space with relative operators like >= 5.
• Prefix types with TypeOp (only for level 4 and 5).
• Example:

(defconst starting-vills-on-sheep 6)
(defrule
	(true)
=>
	(chat-to-all "I need %d villagers on sheep" c: starting-vills-on-sheep)
	(disable-self)
)

• Building conditions:
  • can-build checks if the building is available.
  • sn-initial-exploration-required: Change default from 2 to 0.
  • (housing-headroom < 4): Example condition for housing.