History VideoGame / EuropaUniversalis

* ObviousBeta: New patches for ''[=EU4=]'' often have some things that can be exploited or minor bugs, but some have stood out as almost completely broken.
** The Cossacks DLC (released with patch 1.14) was infamously broken. It introduced new, back then paid content - estates. They weren't fully functional until entire string of patches under 1.14.x numeral, until eventually reaching 1.15.1. Estates were behaving randomly and pressing new demands each month, punishing everyone for refusing their demands, while AI was handling out privileges like candy during peace time, ending up crippled economically and military for no real reason. Things were so bad that the titular Cossack estate, intended to be limited to steppe provinces, was possible to simply install whenever, while still displaying the tooltip about steppes.
** The release of 1.30 (Imperator) was an unmitigated disaster. Every single new mechanic was so fundamentally bugged it should have been obvious to any QA tester within a single run as any European country. Nations would join the HRE at the drop of a hat, leading to everyone from Byzantium to Novgorod to Brittany creating a bloc impervious to outside expansion by 1450. Imperial incidents were broken, with the Shadow Kingdom event leading to Italian nations leaving the HRE and then rejoining the next day. The Council of Trent frequently simply did not fire at all, when it was a major mechanic in the new patch. Mercenary regiments could be split by loading some of them on to transports to recreate the old mercenary system. New events (like estate statutory rights) would pop up every day if they could, completely breaking players games. Most of these were fixed fairly quickly, but it was an astonishingly poorly tested product that had itself been developed over ''an entire year'' to give the team more time to implement and test good features. Instead, it created an impression no testing at all was made, with predictable reception.
** Release 1.31 (Leviathan) was no better. Just to name a few: horde ideas giving a bonus that gave ''+100% conversion speed'' [[note]] as in, provinces are converted in ''one month''[[/note]], North American natives constantly joining and leaving federations, extremely unbalanced buffs from monuments, [[https://www.reddit.com/r/eu4/comments/n1181t/you_can_cancel_monument_construction_in_other/ the possibility to cancel constructions in other countries]], crashes when hovering over some native Australian government reforms, one naval battery disabling piracy in the whole world, going over government capacity as a stateless society giving a bonus rather than a malus, broken announcements, [[https://www.reddit.com/r/eu4/comments/n0339g/i_see_your_666_ruler_and_raise_you_a_buggy_update/ character stats overflowing]], placeholder art still being present for the Sikh religion and, perhaps most egregiously of all Majapahit, ''which is the name of the free release'', being completely unplayable without the DLC due to having no way of preventing the "Collapse of Majapahit" disaster that will without fail kill you.
*** 1.31.1, coming just a few days after, corrected some of the most major glitches and did some rebalancings... [[DoubleSubverted unfortunately, this hotfix itself introduced new glitches]], including Ming spontaneously exploding, and especially a very dangerous glitch capable of wiping out savefiles outright by erasing every single nations in the game.

** With the ''Lions of the North'' DLC, ''IV'' introduced the concept of branching missions, missions where the name, description, requirements and effects are decided by a path selected earlier on. Generally, one path is the historic one in terms of ambitions, while the others go in different directions. This can range from comparatively minor differences like Sweden having the choice to pursue personal union, conquest or alliance with Poland to massive shifts that impact the entire course of the campaign, like the Teutonic Order having a choice between secularization and going towards becoming Prussia (in turn then subdividing into integrating into the Holy Roman Empire, conquering and forming Germany or consolidating an eastern Prussian Kingdom) or doubling down on being an eastern crusader order.

** Cavalry start out much stronger than Infantry, but by end game the firepower and low cost of infantry make them much more useful (and the way math is done on flanking helps as well). Both of them also pale before the sheer obliteration wrought by [[GlassCannon Cannons]], so much that you might find your Infantry as merely [[JustForPun Cannon]] [[WeHaveReserves Fodder]].

** In 1.35 and possibly earlier in 'IV', you can offer to release your territories as independent countries to get out of a losing war. The AI will accept it, even if the released countries are historically friendly to you (even if they're not, they're likely to be afraid of you) and will eventually agree to be diplomatically annexed again. This allows you to expand wildly and simply release a few small territories in the ensuing coalition punitive war to keep most of your gains.

** Release 1.31 (Leviathan) was no better. Just to name a few: horde ideas giving a bonus that gave ''+100% conversion speed'' [[note]] as in, provinces are converted in ''one month''[[/note]], North American natives constantly joining and leaving federations, extremely unbalanced buffs from monuments, crashes when hovering over some native Australian government reforms, one naval battery disabling piracy in the whole world, going over government capacity as a stateless society giving a bonus rather than a malus, broken announcements, placeholder art still being present for the Sikh religion and, perhaps most egregiously of all Majapahit, ''which is the name of the free release'', being completely unplayable without the DLC due to having no way of preventing the "Collapse of Majapahit" disaster that will without fail kill you.

** With the ''Lions of the North'' DLC, ''IV'' introduced the concept of branching missions, missions where the name, description, requirements and effects are decided by a path selected earlier one. Generally, one path is the historic one in terms of ambitions, while the others go in different directions. This can range from comparatively minor differences like Sweden having the choice to pursue personal union, conquest or alliance with Poland to massive shifts that impact the entire course of the campaign, like the Teutonic Order having a choice between secularization and going towards becoming Prussia (in turn then subdividing into integrating into the Holy Roman Empire, conquering and forming Germany or consolidating an eastern Prussian Kingdom) or doubling down on being an eastern crusader order.

* BackFromTheBrink: Playing as Byzantium. The first mission's description says "The empire is but a shadow of itself after repeated blows from the [[UsefulNotes/TheOttomanEmpire the Turk]]...we must reclaim the Greek lands."

** With the ''Lions of the North'' DLC, ''IV'' introduced the concept of branching missions, missions where the name, description, requirements and effects are decided by a path selected earlier one. Generally, one path is the historic one in terms of ambitions, while the others go in different directions. This can range from comparatively minor differences like Sweden having the choice to pursue personal union, conquest or alliance with Poland to massive shifts that impact the entire course of the campaign, like the Teutonic Order having a choice between secularization and going towards becoming Prussia or doubling down on being an eastern crusader order.

*** Despite the presence of a "West Slavic" culture group, Slovak belongs to the "Carpathian" culture group together with Hungarian. This is justifiable since Slovakia was, for most of the historical period of the game, part of the Kingdom of Hungary, so having the two in the same culture group reduces foreign culture penalties.