What is the default AI Embarkation Cost game rule in CK3?

Default: The AI, much like the player, has to pay Gold to Embark. (patch 1.20.1.2)

Does changing the AI Embarkation Cost rule disable achievements?

No: none of its 2 settings carries the flag blocks_achievements in patch 1.20.1.2.

What does AI Embarkation Cost: None change?

AI rulers get Embarkation Cost -100%.

Game rule · Difficulty · AI · Tweaks

AI Embarkation Cost

Default
None

AI Embarkation Cost is a game rule in Crusader Kings III (Difficulty, AI and Tweaks) with 2 settings: Default (the default) and None. None of its settings disables achievements. 1 setting applies modifiers, e.g. None: Embarkation Cost -100%. Patch 1.20.1.2, from game/common/game_rules/00_game_rules.txt.

This section as JSON: /raw/game-rules.json

Quick answers (3)

What is the default AI Embarkation Cost game rule in CK3?: Default: The AI, much like the player, has to pay Gold to Embark. (patch 1.20.1.2)
Does changing the AI Embarkation Cost rule disable achievements?: No: none of its 2 settings carries the flag blocks_achievements in patch 1.20.1.2.
What does AI Embarkation Cost: None change?: AI rulers get Embarkation Cost -100%.

2 settings

Default
Default
The AI, much like the player, has to pay Gold to Embark.
regular_embarkation_costs
None
The AI, unlike the player, doesn't pay Gold to Embark.
AI rulers get the modifier no_embarkation_cost (“No Embarkation Cost”):
- Embarkation Cost-100%
no_ai_embarkation_costs

Source: game/common/game_rules/00_game_rules.txt line 1088 (key ai_embarkation_cost), modifiers from game/common/modifiers, names from the English localisation; Crusader Kings III 1.20.1.2.