Crusader Kings III 1.20.1.2

Game rules that disable achievements

28 settings in 21 rules carry the flag blocks_achievements. Every other setting — and every setting of the other 65 rules — keeps achievements on.

In Crusader Kings III 28 game rule settings disable achievements (the flag blocks_achievements), in 21 rules: Difficulty: Easy, Difficulty: Very Easy, Gender Equality: Equal, Black Death Frequency: Never, Minor Diseases: Fewer and Elderly Health: None. Patch 1.20.1.2, from game/common/game_rules.

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

Settings that disable achievements

Rule	Setting	The rule's default	What the setting does
Difficulty	Easy	Normal	You will be given bonuses, such as lessening the impact of disease, hostile schemes and stress. It will also be easier to handle Factions.
Difficulty	Very Easy	Normal	You will be given significant bonuses, such as lessening the impact of disease, hostile schemes and stress. It will also be much easier to handle Factions.
Gender Equality	Equal	Default	All gender-related Doctrines and Laws are set to Equal. The same rules and rights apply to all characters, regardless of gender.
Black Death Frequency	Never	Once	The Black Death will never occur.
Minor Diseases	Fewer	Default	Minor diseases will appear less often.
Elderly Health	None	Default	Aging comes without risk.
Same-Sex Relations	Accepted	Default	Same-sex relations are fully accepted by all Faiths.
Same-Sex Marriage	Accepted	Default	Same-sex marriage and concubinage is available for everyone whose Faith accepts it, and whose culture practices concubinage. To enable for everyone set the Same-Sex Relations Game Rule to Accepted!
Adoption	Always Allowed	Default	The Adoption Interaction will be available to all characters as long as they are unmarried or the dominant partner in their marriage.
Divergent & Hybrid Culture Cooldowns	No Cooldowns	Default	There are no cooldowns for when a Culture is allowed to Diverge or Hybridize.
Mongol Invasion	Never	Default	The Mongols will not invade.
Casus Belli Costs	No Costs	Default	Casus Bellis are free to use, without any associated costs.
Culture Conversion Speed	Faster	Default	The speed is increased, making conversion take roughly half of the time.
Culture Conversion Speed	Significantly Faster	Default	The speed is significantly increased, making conversion take roughly a quarter of the time.
Faith Conversion Speed	Faster	Default	The speed is increased, making conversion take roughly half of the time.
Faith Conversion Speed	Significantly Faster	Default	The speed is significantly increased, making conversion take roughly a quarter of the time.
Diplomatic Range	Unrestricted	Default	Diplomatic range is turned off, allowing anyone on the map to interact with anyone else.
Faith Acceptance	Full	Default	All Faiths have full acceptance towards other Faiths. There are no Opinion penalties for having a different Faith.
Randomized Faiths & Rites	On	Off	Characters and Counties are assigned random Faiths, and a random Rite within that Faith. All Faiths in the game are available.
Random Ruler Placement	On	Off	Rulers are randomly placed on the map. The Realms are largely the same, but Titles are held by different rulers.
Random Ruler Placement	On (Conversion)	Off	Rulers are randomly placed on the map. They convert to the historical holder's Faith.
Domain Limit	+1, player only	Default	The Domain Limit is increased by one for players.
Domain Limit	+2, player only	Default	The Domain Limit is increased by two for players.
Domain Limit	+3, player only	Default	The Domain Limit is increased by three for players.
Hungarian Migration	Player-Only	Immediate	The AI will not attempt to start the Hungarian Migration.
Scandinavian Adventurers	Rare	Frequent	Scandinavian adventurers will try to target Russia and the North Sea every 15 years.
Scandinavian Adventurers	Off	Frequent	Scandinavian adventurers will never try to target Russia or the North Sea.
Seljuk Invasion	Never	Default	The Seljuks will not invade.

Rules that keep achievements with any setting

Source: the flag = blocks_achievements lines of game/common/game_rules (the flag is documented in its _game_rules.info: “Achievements are disabled while this setting is active”), Crusader Kings III 1.20.1.2. Other things the game checks before it counts an achievement are not in these files. See all achievements.