History YMMV / CrusaderKingsIII

** The implementations of Innovations meant that in 867, Feudal or Tribal characters often ''can't use de jure Claims'' to declare war, or even ''revoke titles''. Tribal characters at least get the 'county conquest', 'duchy conquest', and 'invasion' [=CBs=] for free, but Feudal characters often get stuck having to fabricate for everything or taking the Diplomacy tree for its 'vassalization' CB unless they neighbor religious enemies or follow a faith with the Pursuit of Power or Warmongering tenets, which enable feudal characters to use the [=CBs=] that are normally only available to tribal characters.
** Stress triggers are not distributed evenly across traits, with some traits having fairly lenient and logical conditions of what gives or loses you stress, and some not so much. The 'Shy' trait more or less ruins any social ability of your character by making every social scheme (sway, befriend, seduce, romance) ''and'' most social interactions (like throwing feasts) either cause stress or cause no stress loss, while Greedy and Ambitious stresses you out whenever you give away money or parcel out land (ironically making Ambitious one of the ''worst'' traits for an expansionist character who wants to expand their power, since handling out new lands and titles stresses you out). Your traits, furthermore, do not seem to influence your educational trait, meaning Just or Compassionate characters get screwed if they gain Intrigue education (since torturing prisoners and practically all hostile schemes stress them out). The issues with Ambitious and Greedy were at least fixed in 1.1 by making it so land above one's domain limit could be given away stress-free.

** Pagan Gavelkind[[note]]where your heirs automatically get any highest-tier title you could legally create for free, and become independent if those titles are the same tier as your primary one[[/note]] (or 'Confederate Partition') is back from its predecessor games, as annoying as ever, and the only available succession option until 900 (when 'classical' Gavelkind or Partition becomes available). Unless you usurp the Byzantine Empire (which has Primogeniture by default) or belong to a culture that can switch to an Elective mode of succession[[note]]Norse, Saxon, Celtic, or Feudal realms (but not Muslim Clans), and even then you aren't guaranteed your counties will go Elective so your demesne will still get split up[[/note]], expect your realm to get divvied up into independent states every time your character croaks it. Single-heir inheritance isn't available before the High Middle Ages, and even then only Seniority, and Primogeniture/Ultimogeniture is only available for the last 250 years provided you can instantly research and implement it. Pre-1.1 this was even more annoying as the title of Dynasty Head, as well as any unlanded titles (like religious head) would still get passed down the main line of descent instead of being given to the player's primary heir.

** CK2 Pagan Gavelkind[[note]]where your heirs automatically get any highest-tier title you could legally create for free, and become independent if those titles are the same tier as your primary one[[/note]] (or 'Confederate Partition') is back from its predecessor games, as annoying as ever, and the only available succession option until 900 (when 'classical' Gavelkind or Partition becomes available). Unless you usurp the Byzantine Empire (which has Primogeniture by default) or belong to a culture that can switch to an Elective mode of succession[[note]]Norse, Saxon, Celtic, or Feudal realms (but not Muslim Clans), and even then you aren't guaranteed your counties will go Elective so your demesne will still get split up[[/note]], expect your realm to get divvied up into independent states every time your character croaks it. Single-heir inheritance isn't available before the High Middle Ages, and even then only Seniority, and Primogeniture/Ultimogeniture is only available for the last 250 years provided you can instantly research and implement it. Pre-1.1 this was even more annoying as the title of Dynasty Head, as well as any unlanded titles (like religious head) would still get passed down the main line of descent instead of being given to the player's primary heir.

** Stress triggers are not distributed evenly across traits, with some traits having fairly lenient and logical conditions of what gives or loses you stress, and some not so much. The 'Shy' trait more or less ruins any social ability of your character by making every social scheme (sway, befriend, seduce, romance) ''and'' most social interactions like throwing feasts cause stress or having your stress loss, while Greedy and Ambitious stresses you out whenever you give away money or parcel out land (ironically making Ambitious one of the ''worst'' traits for an expansionist character who wants to expand their power, since handling out new lands and titles stresses you out). Your traits, furthermore, do not seem to influence your educational trait, meaning Just or Compassionate characters get screwed if they gain Intrigue education (since torturing prisoners and practically all hostile schemes stress them out). The issues with Ambitious and Greedy were at least fixed in 1.1 by making it so land above one's domain limit could be given away stress-free.

** Fervor, which replaces Moral Authority from the previous game. Unlike Moral Authority, which went up when anyone of your faith won a holy war and down when they lost in what was admittedly potentially painful UnstableEquilibrium, Fervor goes down on winning or losing as the attacker in a holy war and increases on losing as the defender in a holy war (winning as the defender in a holy war has no effect on one's own Fervor). As Fervor goes down, outbreaks of heresy become more common and the realm priest county conversion mission becomes less effective. Additionally, passive Fervor growth is negatively modified by the size of a faith. When compounded by the Sinful Priest event (which also fires more often for faiths that have more land) and the lack of other easily available [=CBs=] for feudal rulers, this commonly results in Catholicism (and to a lesser extent, Ash'ari Sunni Islam) imploding into heresy as its massive size stymies Fervor growth and its numerous rulers burn away its Fervor on numerous individual holy wars with further hits from sinful priests. Also, with little ability to religiously stabilize their realm after a Crusade (a Crusade leads to a ''60'' point Fervor shift between winner and loser), Crusader states have become infamous for swiftly converting to the local religion (or simply being overthrown by religious rebels), leading to several successive crusades for the exact same kingdom to depose the previous winners.

** The implementations of Innovations meant that in 867, Feudal or Tribal characters often ''can't use de jure Claims'' to declare war, or even ''revoke titles''. Tribal characters at least get the 'county conquest' CB for free, but Feudal characters get stuck having to fabricate for everything or taking the Diplomacy tree for its 'vassalization' CB.

** The Seduction mechanic is back from its original form in ''Ways of Life'' for the second game, and now that every AI character can use it, expect everybody to get seduced nearly constantly. A reddit user looking into the matter discovered that the game is actually coded so that discovering a love affair can retroactively change a child's parentage from its actual parent to the lover, which is fairly immersion breaking for players wanting to roleplay a family tree. It's especially jarring because said event ignores IncompatibleOrientation - even homosexual or asexual women can be retroactively revealed to have had an affair with another man [[MamasBabyPapasMaybe and passed off a child born of that affair as the player's]].

* GameBreaker: The game was broken before release thanks to Paradox handing a preview copy to ''WebVideo/TheSpiffingBrit''. Several of his strategies are still eminently breakable in-game, while others are since fixed.
** Catholic and Orthodox rulers (as well as any monogamous religions with a religious head) can divorce their spouse for 100 piety, and gain up to 300 Fame (which gatekeeps access to the more advanced ''CasusBelli'') for marrying again. In the early game, where teching up your Fame is a lot more useful than piety, becoming a serial divorcer (often of the same character) is an extremely lucrative exchange.
** The "Golden Obligations" feat from the Avaricious tree (the first one obtainable) allows you to blackmail people for their hooks, granting you gold (usually up to 100, scaling with titles). Given the [=AIs=] enormous fondness for seductions in the base game, parking a halfway-decent spymaster with a good intrigue in the court of a nearby king can easily net you hooks worth several hundred gold a year.
** ''Crusader Kings II's'' infamous "North Korea mode" in the 1.0 release, wherein a player simply doesn't bother with vassals and holds everything directly, was still powerful in the release version of ''III''. Since the over-domain penalties on taxes and levies were capped at 90%, it remained a net gain at ten times the normal domain limit, and allows absurd stacking of man-at-arms bonuses, allowing one's men-at-arms to be able to annihilate armies dozens of times their size with no effort, at least until they become so powerful that they hit an integer overflow and cause negative casualties. Eventually fixed by ObviousRulePatch in 1.1; the penalty cap was raised to ''100%'', ,and buildings (including those that provide the man-at-arms bonuses) deactivate if a player is far over their domain limit for longer than the one-year grace period for handing out newly-conquered titles.
** Abduction initially allowed for some hilariously broken exploits. One could very easily use it to win wars against far more powerful foes by kidnapping the enemy ruler and forcing them to come to terms. Also fixed via ObviousRulePatch in 1.1; foreigners, especially foreign rulers, have greater resistance to the abduct scheme, and this is raised even further if the ruler is at war with the schemer.
** For Catholics and Orthodox characters, the Pope/Ecumenical Patriarch is best looked at as a piggy bank in a very NiceHat. Both take a cut from the income of ''every'' Catholic/Orthodox temple holding on the map, which means they usually have lots of it to give away (especially the Pope), and will do so readily for 250 piety and a small opinion hit once per decade. Asking the Pope for money will give you enough to buy your way out of having to go Crusading as well.
** The dread mechanic becomes hilariously broken once you realize that non-faith prisoners cost no piety to execute, or worse yet, some religions ''gain'' piety by executing heathens. Due to the wonky fervor mechanic at launch, it's extremely easy to acquire heathen prisoners because heretical faiths prop up everywhere. The piety cost is the main bottleneck against executing prisoners, and with it gone, you can easily max out your dread and be completely safe from factions.

** Stress triggers are not distributed evenly across traits, with some traits having fairly lenient and logical conditions of what gives or loses you stress, and some not so much. The 'Shy' trait more or less ruins any social ability of your character by making every social scheme (sway, befriend, seduce, romance) ''and'' most social interactions like throwing feasts cause stress or having your stress loss, while Greedy and Ambitious stresses you out whenever you give away money or parcel out land (ironically making Ambitious one of the ''worst'' traits for an expansionist character who wants to expand their power, since handling out new lands and titles stresses you out). Your traits, furthermore, do not seem to influence your educational trait, meaning Just or Compassionate characters get screwed if they gain Intrigue education (since torturing prisoners and practically all hostile schemes stress them out).

** ''Crusader Kings II's'' infamous "North Korea mode" in the 1.0 release, wherein a player simply doesn't bother with vassals and holds everything directly, is more viable than ever in the release version of ''III''. Since the over-domain penalties on taxes and levies was capped at 90%, it's still a net gain at ten times your normal domain limit, but on top of that, it allows absurd stacking of man-at-arms bonuses, allowing one's men-at-arms to be able to annihilate armies dozens of times their size with no effort, at least until they become so powerful that they hit an integer overflow and cause negative casualties. Eventually fixed by ObviousRulePatch in 1.1; the penalty cap was raised to ''100%'', ,and buildings (including those that provide the man-at-arms bonuses) deactivate if a player is far over their domain limit for longer than the one-year grace period for handing out newly-conquered titles.

* GameBreaker: The game was broken before release thanks to Paradox handing a preview copy to ''WebVideo/TheSpiffingBrit''. Several of his strategies are still eminently breakable in-game.

** Abduction allows for some hilariously broken exploits. One can very easily use it to win wars against far more powerful foes by kidnapping the enemy ruler and forcing them to come to terms. Also fixed via ObviousRulePatch in 1.1; foreigners, especially foreign rulers, have greater resistance to the abduct scheme, and this is raised even further if the ruler is at war with the schemer.

** ''Crusader Kings II's'' infamous "North Korea mode", wherein a player simply doesn't bother with vassals and holds everything directly, is more viable than ever in the release version of ''III''. Since the over-domain penalties on taxes and levies are capped at 90%, it's still a net gain at ten times your normal domain limit, but on top of that, it allows absurd stacking of man-at-arms bonuses, allowing one's men-at-arms to be able to annihilate armies dozens of times their size with no effort, at least until they become so powerful that they hit an integer overflow and cause negative casualties.
** Abduction allows for some hilariously broken exploits. One can very easily use it to win wars against far more powerful foes by kidnapping the enemy ruler and forcing them to come to terms.

* AscendedExtra: Faiths of a dualistic nature. This includes Zoroastrianism, which was a popular religious option in the previous game, but generally only played a role if players actively devoted themselves to restoring it, as well as a couple of minor, related Gnostic Christian heresies, of which similar things can be said for the most part. Come this game and, in addition to the aforementioned Christian dualists still existing, there is now a whole new Dualistic religious group with half a dozen separate, extremely obscure faiths, as well as another half-dozen new Zoroastrian heresies and an unexpectedly thorough amount of support for playing a Gnostic of any kind, even letting you add Gnosticism specifically as a feature when founding a new faith. Note that most of these religions have been dead for centuries by the time-frame of ''Crusader Kings 3'' and that, unless you use the (non-default) very strict historical heresy setting, ''they can now randomly pop up anywhere''.
** The amount of available heresies in general has been greatly expanded, as has their prominence. In the previous game, without player intervention, it was rare to see any of them stick around for more than a few years, much less really take off and replace a country's state religion. In this game, because the Fervor mechanics heavily penalize large religions (such as, for example, ''Catholicism''), it is now very common for heresy to thrive. Unless you do something to stop it, do not be surprised to see by the end of the game things like half of Europe converted to Lollardy, or the Middle East to be entirely dominated by the Armenian Apostolic Church.

* AscendedExtra: Faiths of a dualistic nature. This includes Zoroastrianism, which was a popular religious option in the previous game, but generally only played a role if players actively devoted themselves to restoring it, as well as a couple of minor, related Gnostic Christian heresies, of which similar things can be said for the most part. Come this game and, in addition to the aforementioned Christian dualists still existing, there is now a whole new Dualistic religious group with half a dozen separate, extremely obscure faiths, as well as another half-dozen new Zoroastrian heresies and an unexpectedly thorough amount of support for playing a Gnostic of any kind, even letting you add Gnosticism specifically as a feature when founding a new faith. Note that most of these religions have been dead for centuries in the time-frame of ''Crusader Kings 3'' and that, unless you use the (non-default) very strict historical heresy setting, ''they can now randomly pop up as a heresy anywhere''.

* AscendedExtra: Faiths of a dualistic nature. This includes Zoroastrianism, which was a popular religious option in the previous game, but generally only played a role if players actively devoted themselves to restoring it, as well as a couple of minor, related Gnostic Christian heresies, of which similar things can be said for the most part. Come this game and, in addition to the aforementioned Christian dualists still existing, there is now a whole new Dualistic religious group with half a dozen separate, extremely obscure faiths, as well as another half-dozen new Zoroastrian heresies and an unexpectedly thorough amount of support for playing a Gnostic of any kind, even letting you add Gnosticism specifically as a feature when founding a new faith.

* AscendedExtra: Zoroastrianism was a popular religious option in the previous game, but generally only played a role if players actively devoted themselves to restoring it. There were also a couple of minor, related Gnostic heresies. Come this game and there are now literally a dozen or so separate, extremely obscure Dualist and Zoroastrian faiths and sub-heresies and an unexpectedly thorough amount of support for playing a Gnostic of any kind.

** Fervor, which replaces Moral Authority from the previous game. Unlike Moral Authority, which went up when anyone of your faith won a holy war and down when they lost in what was admittedly potentially painful UnstableEquilibrium, Fervor goes down on winning or losing as the attacker in a holy war and increases on losing as the defender in a holy war (winning as the defender in a holy war has no effect on one's own Fervor). As Fervor goes down, outbreaks of heresy become more common and the realm priest county conversion mission becomes less effective. Additionally, passive Fervor growth is negatively modified by the size of a faith. When compounded by the Sinful Priest event (which also fires more often for faiths that have more land) and the lack of other easily available [=CBs=] for feudal rulers, this commonly results in Catholicism (and to a lesser extent, Ash'ari Sunni Islam) imploding into heresy as its massive size stymies Fervor growth and its numerous rulers burn away its Fervor on numerous individual holy wars with further hits from sinful priests. Also, with little ability to religiously stabilize their realm after a Crusade, Crusader states have become infamous for swiftly converting to the local religion, leading to several successive crusades for the exact same kingdom to depose the previous winners.
** Crusades, and Crusader Kingdoms, in general. Like in post-''Holy Fury'' ''Crusader Kings 2'', crusades (provided you're not re-taking lost ground) force you to hand the conquered lands over to an unlanded candidate of your dynasty. Following a successful crusade, the 'winner' is stuck with a bunch of 0-control lands of a different culture and religion, usually containing into counties held by the other crusade participants' candidates and making the state very decentralized. The unfortunate crusader king will usually find the new lands extremely hard to convert due to the Fervor mechanic (seen above) causing a ''60'' point swing between the victor and the defeated (+/-30 Fervor for winning/losing a crusade), and will usually either get overthrown by an independence faction by the counties themselves or convert to the native culture/religion within a decade, rendering the whole affair moot by leaving the land exactly as they were found and usually forcing a ''new'' Crusade to re-take the lands lost in the last crusade.

** Crusades, and Crusader Kingdoms, in general. Like in post-''Holy Fury'' CK2, crusades (provided you're not re-taking lost ground) force you to hand the conquered lands over to an unlanded candidate of your dynasty, stuck with a bunch of 0-control lands of a different culture and religion. The unfortunate crusader king will usually find the new lands extremely hard to convert due to the Fervor mechanic (seen above), and will usually either get overthrown by an independence faction by the counties themselves or convert to the native culture/religion within a decade. Given they cost a massive ''30'' Fervor, crusades usually just end up ruining whatever religion has them for very little gain.

* AscendedExtra: Zoroastrianism was a popular religious option in the previous game, but generally only played a role if players actively devoted themselves to restoring it. There were also a couple of minor, related Gnostic heresies. Come this game and there are now literally a dozen or so separate, extremely obscure Dualist and Zoroastrian faiths and sub-heresies.

** Fervor, which replaces Moral Authority from the previous game. Unlike Moral Authority, which went up when anyone of your faith won a holy war and down when they lost in what was admittedly potentially painful UnstableEquilibrium, Fervor goes down on winning or losing as the attacker in a holy war and increases on losing as the defender in a holy war (winning as the defender in a holy war has no effect on one's own Fervor). As Fervor goes down, outbreaks of heresy become more common and the realm priest county conversion mission becomes less effective. Additionally, passive Fervor growth is negatively modified by the size of a faith. When compounded by the Sinful Priest event (which also fires more often for faiths that have more land) and the lack of other easily available [=CBs=] for feudal rulers, this commonly results in Catholicism (and to a lesser extent, Ash'ari Sunni Islam) imploding into heresy as its massive size stymies Fervor growth and its numerous rulers burn away its Fervor on numerous individual holy wars with further hits from sinful priests. Also, with little ability to religiously stabilize their realm after a Crusade, Crusader states have become infamous for swiftly converting to the local religion, leading to several successive crusades for the exact same kingdom to depose the previous winners.

* Fervor, which replaces Moral Authority from the previous game. Unlike Moral Authority, which went up when anyone of your faith won a holy war and down when they lost in what was admittedly potentially painful UnstableEquilibrium, Fervor goes down on winning or losing as the attacker in a holy war and increases on losing as the defender in a holy war (winning as the defender in a holy war has no effect on one's own Fervor). As Fervor goes down, outbreaks of heresy become more common and the realm priest county conversion mission becomes less effective. Additionally, passive Fervor growth is negatively modified by the size of a faith. When compounded by the Sinful Priest event (which also fires more often for faiths that have more land) and the lack of other easily available [=CBs=] for feudal rulers, this commonly results in Catholicism (and to a lesser extent, Ash'ari Sunni Islam) imploding into heresy as its massive size stymies Fervor growth and its numerous rulers burn away its Fervor on numerous individual holy wars with further hits from sinful priests. Also, with little ability to religiously stabilize their realm after a Crusade, Crusader states have become infamous for swiftly converting to the local religion, leading to several successive crusades for the exact same kingdom to depose the previous winners.

** Stress triggers are not distributed evenly across traits, with some traits having fairly lenient and logical conditions of what gives or loses you stress, and some not so much. The 'Shy' trait more or less ruins any social ability of your character by making every social scheme (sway, befriend, seduce, romance) ''and'' most social interactions like throwing feasts cause stress or having your stress loss, while Greedy and Ambitious stresses you out whenever you give away money or parcel out land (ironically making Ambitious one of the ''worst'' traits for an expansionist character who wants to expand their power, since handling out new lands and titles stresses you out). Your traits, furthermore, do not seem to influence your educational trait, meaning Just or Compassionate characters get screwed if they gain Intrigue education (since torturing prisoners and practically all hostile schemes stress them out).

** Catholic and Orthodox rulers (as well as any monogamous religions with a religious head) can divorce their spouse for 100 piety, and gain up to 300 Prestige for marrying again. In the early game, where prestige is used for a lot more than piety, this becomes an extremely lucrative exchange.

* ScrappyMechanic: The Seduction mechanic is back from its original form in ''Ways of Life'' for the second game, and now that every AI character can use it, expect everybody to get seduced nearly constantly. A reddit user looking into the matter discovered that the game is actually coded so that discovering a love affair can retroactively change a child's parentage from its actual parent to the lover, which is fairly immersion breaking for players wanting to roleplay a family tree. It's especially jarring because said event ignores IncompatibleOrientation - even homosexual or asexual women can be revealed to have had an affair with another man [[MamasBabyPapasMaybe and passed off a child born of that affair as the players]].
** The implementations of Innovations meant that in 867, Feudal or Clan characters often ''can't use de jure Claims'' to declare war, or even ''revoke titles''.

* ScrappyMechanic: The Seduction mechanic is back from its original form in ''Ways of Life'' for the second game, and now that every AI character can use it, expect everybody to get seduced nearly constantly. A reddit user looking into the matter discovered that the game is actually coded so that discovering a love affair can retroactively change a child's parentage from its actual parent to the lover, which is fairly immersion breaking for players wanting to roleplay a family tree. It's especially jarring because said event ignores IncompatibleOrientation - even homosexual or asexual women can be revealed to have had an affair with another man [[MamasBabyPapasMaybe and passed off a child born of that affair as the players]].

* ScrappyMechanic: The Seduction mechanic is back from its original form in ''Ways of Life'' for the second game, and now that every AI character can use it, expect everybody to get seduced nearly constantly. A reddit user looking into the matter discovered that the game is actually coded so that discovering a love affair can retroactively change a child's parentage from its actual parent to the lover, which is fairly immersion breaking for players wanting to roleplay a family tree.