Europa Universalis IV

Players navigate their nations through trade, administration, diplomacy, colonization, and warfare. The game has sold over 4 million copies as of February 2024.

The game includes different bookmarked starting dates called "scenarios", with the world state, borders and events reflecting their historical equivalents for each. The earliest scenarios begin on 11 November 1444, one day after the Christian defeat at Varna, while the latest scenario begins on 21 September 1792, the end of the French monarchy. The player can also choose any day within the games time span as a starting date. The game itself is an interactive map of Earth divided into the provinces that compose nations. Each of these provinces contribute to their country either positively or negatively, as provinces can both provide resources to a nation and serve as a point of unrest and rebellion. At the beginning of the game many provinces are considered "uncolonized" and are meant to represent possible land colonizable by other nations. The gameplay requires the player to lead a nation by finding a balance of military, diplomacy, and economy. The player does so through their choices as sovereign of their nation, and the spending of resources available to them: prestige, power projection, stability, gold (ducats), manpower, legitimacy for monarchies, republican tradition for republics, devotion for theocracies, horde unity for steppe nomads, meritocracy for celestial empires, and monarch power (administrative, diplomatic, and military). Players can choose to conquer the world by military might, become a colonial superpower, establish trade dominance, etc. as one of over 500 different nations. The game is a sandbox environment; there is no strict win condition for players. A player's game ends when the player's nation is annexed (removed from the map) or when the in-game date reaches 3 January 1821. Diplomacy is a large aspect of the game, as creating alliances (or vassal states and tributaries), improving opinions, and preventing defensive coalitions are vital to a player's survival. Espionage can also be employed against enemy states to claim their territory or incite rebellion in their provinces, along with other dubious ends. Combat can be waged on both land and sea, during which the game attempts to simulate real-world factors such as morale, discipline, varying unit types with associated strengths and weaknesses, competency of leaders, terrain, and supply lines. Trade is also an important part of the game, where the world is divided into many trade nodes, and trade flows through each of the nodes and can be collected by merchants. Many major religions, such as Catholicism, Orthodox Christianity, Protestantism, Sunni Islam, and Shia Islam, are present in the game and can provide distinct bonuses to their practitioners. Players can employ missionaries to convert their provinces or can engage in policies of universal religious freedom. For example, the Catholic faith makes use of the Papacy, which can allow a nation to have control over the Pope or to use its influence for other rewards. Native American and Aboriginal religions are also present in the game, most commonly utilizing a system of selecting a bonus for the lifetime of the present monarch. Furthermore, many of the world's institutions, from feudalism to industrialization, are also present in the game. Institutions normally appear around a certain year, and begin spreading through provinces. The rate of institution spread and where the institution spawns are malleable to player actions. Once reaching requirements, usually consisting of a ducat cost and a certain amount of institutions present in the player's provinces, the player can embrace the institution. Foregoing embracing an institution for too long increases a nation's technology cost; embracing an institution gives an institution-specific nation bonus, as well as purging any technological maluses that the lack of institution may have incurred. Technological advancements are invested in over time, and require the expense of monarch points. They provide benefits to the nation as detailed below: Administrative technology unlocks advancements such as increased productivity, new forms of government, new buildings, and the national idea system. Diplomatic technology unlocks advancements such as naval units, improvements in trade, new buildings, and improved colonial expansion. Military technology unlocks advancements such as new types of land units, improved unit morale, combat tactics, and new buildings. Gameplay is influenced by random events that arise periodically for the player. These events can be either helpful or harmful. Some of these random events are driven by an individual country's history, while some can apply to any country and serve generally to enhance the "flavor" of the game. Some events are also motivated by various institutions that occur throughout the history of the game, such as the Industrial Revolution. Players can choose to play single-player mode versus the AI, or multiplayer over a LAN or the Internet against a mix of human and AI opponents. Single-player also has the option of "Ironman" mode, which locks several settings such as difficulty, and removes the control of saving the game from the player. This means that any mistakes are irreversible. It is, however, the only way to receive any of the game's many achievements.

Early design discussions for Europa Universalis IV began shortly after the December 2010 release of Divine Wind, the final DLC for Europa Universalis III with development, based on the Clausewitz Engine, beginning in earnest in about September 2011. It was first announced to the public in August 2012, to coincide with a showing at that year's Gamescom, after having been teased under the codename of "Project Truman". Throughout the game's development, Paradox Development Studio released weekly "developer diaries" via their online forums, in which they detailed some features of the game's development. These included information about design philosophy, game mechanisms that were being implemented, and features from Europa Universalis III that were being removed. During its development, Europa Universalis IV had a greater priority given to stability and quality control than previous games in the series. There had previously been a perception that Paradox's games were not worth buying until several updates or expansions had fixed stability issues. Studio CEO, Fredrik Wester, described this perception as being like "a slap in the face", motivating them to improve. Another of Paradox's major goals was to retain the depth and complexity of their earlier grand strategy games while making them easier for a player to interact with. Before release, a preview version of the game was showcased through Let's Plays and via a multiplayer event for journalists. A playable demo of the game was released on Steam on 9 August 2013 with the game itself being released on 13 August 2013. Following its release, development of the game has continued under the same model that Paradox had previously used successfully for Crusader Kings II, with paid DLCs being released alongside, and helping to fund, additional free patches which add more features to the base game. as of May 2024, twenty-two items of DLC have been released for the game alongside many minor DLCs offering additional graphical or musical options. In September 2020, Paradox Tinto, a newly formed division of Paradox based in Barcelona, Spain, took over the development of the game led by leader Johan Andersson. This team released all the expansions after 2020, while also focusing on bug fixes.

Several downloadable content (DLC) have been released for the game. All DLCs are optional and may be applied to the base game in any combination. The most significant DLCs come in the form of expansions and immersion packs. Expansions bring broader and considerable changes to the game as they introduce new and improved gameplay mechanics along with many kinds of flavor and various balance tweaks. While immersion packs are expansions of a smaller scale as they focus on specific regions to bring them better to life by granting more flavor. There are also flavor packs (which add new events and minor mechanisms, usually specific to one nation), music packs (which add more backing music), and cosmetic packs (which affect unit models, portraits, and the map). There are also three e-books that have no impact on the game itself but coincided with the release of expansions. In March 2021, Paradox unveiled an optional subscription service to play the game's vast library of DLCs without buying each expansion. In September 2024, Paradox announced the integration of Rights of Man, Art of War, and Common Sense into the base game. The DLCs were fully integrated into the base game with patch 1.37.5 in October 2024. Expansions are often accompanied by coinciding free patches to the game, which may adjust existing mechanisms or add new ones to the theme of the expansion.

Aside from the official expansion packs, third-party mods are available on sites such as the Steam Workshop. The mods can change the game's settings, add or remove features and game mechanisms, add new land masses to the "random new world" generator, and make graphical improvements. Popular mods include "Extended Timeline", which expands the game's scope from 2 AD to the present day, the Game of Thrones adaptation "A Song of Ice and Fire" (Renamed "Westeros Universalis: A Game Of Thrones" in May 2023) and The Elder Scrolls adaptation "Elder Scrolls Universalis", to complete overhauls like "MEIOU & Taxes" and fantasy total conversions such as "Anbennar".

In May 2014, Paradox released a book, Europa Universalis IV: What If? The Anthology of Alternate History, a collection of short stories inspired by the game and its period, including one by Harry Turtledove. The book was released as an ebook, as DLC for the game, and as a physical edition. In May 2018, at their PDXCon convention, Paradox announced that board games were being developed based upon four of their franchises, stating that they were on a "mission to expand the IP". The Europa Universalis game (eventually named Europa Universalis: The Price of Power) was designed by Eivind Vetlesen of Aegir Games and has a solo mode by David Turczi. Jonathan Bolding of PC Gamer described a preview version as "something between a high player count Twilight Imperium and A Game of Thrones with a dash of Napoleon in Europe".

On 8 May 2025, the sequel, Europa Universalis V, was announced by Paradox.