Game rules are configuration choices available when starting a new game that can slightly alter some mechanics. Many such option will disable Achievements.
Difficulty
The difficulty setting can grant players the following bonuses:
| Difficulty |  Hostile Scheme Resistance
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 Fertility
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 Short Reign Duration
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Tyranny Gain
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 Stress Gain
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 Knight Survival
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 Minor Disease Chance
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 Health Boost
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 Faction Formation
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Vassal Opinion
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Liege Opinion
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Achievements |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Very Easy | +30 | +20% | -50% | -75% | -50% | +75% | -75% | Moderate | Significantly Slower | +25 | +50 | 
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| Easy | +15 | +10% | -25% | -25% | -25% | +66% | -15% | Small | Slightly Slower | 0 | 0 |
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| Normal | 0 | 0 | 0 | 0 | 0 | 0 | 0 | None | Regular | 0 | 0 | 
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Gameplay options
The gameplay options can change the game to be less historical.
| 规则 | 设置 | 效果 | 成就 |
|---|---|---|---|
| 飞地独立 | 关闭 | 统治者能在世界任何地方拥有飞地。 |
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| 受限（仅限AI） | AI统治者会在和平时期的继承中失去飞地，除非这些飞地经由一个伯爵领或海路与首都地区相连，或是其法理领土的一部分。 |
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| 重要（仅限AI） | AI统治者会在和平时期的继承中失去飞地，除非这些飞地经由海路与首都地区相连，或是其法理领土的一部分。 |
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| 完全（仅限AI） | AI统治者会在和平时期的继承中失去飞地，除非这些飞地经由海路与首都地区相连。 |
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| 受限 | 统治者会在和平时期的继承中失去飞地，除非这些飞地经由一个伯爵领或海路与首都地区相连，或是其法理领土的一部分。 |
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| 重要 | 统治者会在和平时期的继承中失去飞地，除非这些飞地经由海路与首都地区相连，或是其法理领土的一部分。 |
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| 完全 | 统治者会在和平时期的继承中失去飞地，除非这些飞地经由海路与首都地区相连。 |
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| 多人游戏：谋杀阴谋 | 默认 | 玩家可以针对其他玩家和他们的families发动阴谋。 |
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| 禁止玩家 | 玩家不可以针对其他玩家发动阴谋，但可以针对他们的families发动阴谋。 |
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| 禁止玩家至亲 | 玩家不能针对其他玩家和他们的families发动阴谋。 |
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| 次要疾病 | 默认 | 次要疾病会按正常情况出现。 |
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| 更是 | 次要疾病的出现频率会减少30%。 |
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| 性别平等 | Default | All faiths start with their historical views on gender, clerical gender, male adultery and female adultery doctrines All realms start with their historical gender succession law |
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| Equal | All faiths start with the Equal views on gender doctrine and Either clerical gender doctrine All faiths start with male adultery and female adultery doctrines at the same level (the lesser one) All realms start with the Equal gender succession law |
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| Inverted | All faiths start with their historical views on gender, clerical gender, male adultery and female adultery doctrines inverted All realms start with their historical gender succession law inverted |
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| 区域异端 | Strict | Heresies are 200 times more likely to be historical if they happen in certain regions |
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| Default | Heresies are more 5 times more likely to be historical if they happen in certain regions |
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| Relaxed | Heresies are random no matter where they happen |
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| 蒙古入侵 | 默认 | An AI character will use the Become Greatest of Khans decision between the years 1180 and 1250 if the player doesn't do it before |
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| 从不 | Only player characters can use the Become Greatest of Khans decision |
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| 随机 | An AI character can use the Become Greatest of Khans decision at any point if the player doesn't do it before |
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| 宣战理由花费 | 默认 | 宣战理由会花费资源，如虔诚或威望。 |
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| 无花费 | 宣战理由不需要花费资源。 |
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| 文化转变速度 | 大幅减慢 | The Promote Culture councilor task makes progress 4 times slower |
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| 减慢 | The Promote Culture councilor task makes progress 2 times slower |
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| 默认 | The Promote Culture councilor task makes progress as per normal |
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| 加快 | The Promote Culture councilor task makes progress 2 times faster |
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| 大幅加快 | The Promote Culture councilor task makes progress 4 times faster |
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| 信仰转变速度 | Significantly Slower | The Convert Faith in County councilor task makes progress 4 times slower |
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| Slower | The Convert Faith in County councilor task makes progress 2 times slower |
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| Default | The Convert Faith in County councilor task makes progress as per normal |
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| Faster | The Convert Faith in County councilor task makes progress 2 times faster |
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| Significantly Faster | The Convert Faith in County councilor task makes progress 4 times faster |
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| 外交范围 | Restricted | Diplomatic Range is reduced by 25% |
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| Default | Diplomatic Range remains unchanged |
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| Unrestricted | Characters can interact no matter the distance |
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| 结束日期 | 1453 | The game will end in 1453 |
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| No End Date | The game will never end |
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| 法理要求 | On | Every 5 years titles with de jure land will be destroyed if their holder controls none of their de jure land |
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| On (Limited) | Every 5 years titles with de jure land will be destroyed if their holder controls none of their de jure land unless it's a player's primary title |
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| Off | Titles with de jure land can only be destroyed manually |
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| 自建王国 | On | The Found a New Kingdom and Found a New Empire decisions are available |
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| Off | The Found a New Kingdom and Found a New Empire decisions are not available |
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| 生成家庭 | On | Landed characters with no recorded family will start with a spouse, a valid heir, a second child if the mother is over 25 and a third child if the other is over 33 |
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| On (AI Only) | Landed AI characters with no recorded family will start with a spouse, a valid heir, a second child if the mother is over 25 and a third child if the mother is over 33 |
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| Off | Landed characters with no recorded family will not start with any family |
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| 同性关系 | Default | All faiths start with their historical same-sex relations doctrine |
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| Accepted | All faiths start with the Accepted same-sex relations doctrine |
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| 性取向分布 | Default | Characters have a 89% chance to be heterosexual, 5% chance to be homosexual, 5% chance to be bisexual and 1% chance to be asexual |
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| Bisexuality | Characters have a 89% chance to be bisexual, 5% chance to be homosexual, 5% chance to be heterosexual and 1% chance to be asexual |
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| Homosexuality | Characters have a 89% chance to be homosexual, 5% chance to be heterosexual, 5% chance to be bisexual and 1% chance to be asexual |
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| Asexuality | Characters have a 89% chance to be asexual, 3.6% chance to be homosexual, 3.6% chance to be bisexual and 3.6% chance to be heterosexual |
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| Equal | Characters have equal chances to be heterosexual, homosexual, bisexual and asexual |
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| 信仰接受度 | Default | All faiths start with their historical views on other faiths |
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| Full | All faiths start with the Full Tolerance special doctrine |
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| 随机信仰 | Off | All characters and counties start with their historical faith |
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| On | All characters and counties start with a random faith |
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| 随机统治者位置 | Off | All rulers have start with their real historical titles |
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| On | All rulers have start with random historical titles |
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| On (Conversion) | All rulers have start with random historical titles and convert to the faith of their primary title's capital |
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| 角色裸体 | Default | Characters will appear naked in certain events or if they follow a faith with the Natural Primitivism tenet or are Court Chaplains or Zealous and follow a faith with the Naked Priests doctrine |
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| Never | Characters cannot appear naked |
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| 匈牙利人迁徙 | Historical | An AI character will use the Prepare to Cross the Carpathians decision between the years 890 and 910 if the player doesn't do it before |
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| Random | An AI character will use the Prepare to Cross the Carpathians decision between the years 872 and 910 if the player doesn't do it before |
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| Immediate | The Mogyër Confederation starts having used the Prepare to Cross the Carpathians and in a war against the Kingdom of Bulgaria using the Migrate to Pannonia casus belli |
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| Player-Only | Only player characters can use the Prepare to Cross the Carpathian decision |
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Ironman
Ironman is a special game rule that disables character switching and manual saving. The game is saved automatically once every 6 months as well as when exiting the game. Achievements can only be obtained in Ironman mode. In Ironman mode, the game over screen only has the option to exit to the main menu.