Inventions represent specific technologies or practices that can be adopted by the state in order to get a specific military, economic, or political effects and bonuses. Every invention is associated with a specific field of advances and is structured as part of a tree, with most inventions requiring prerequisites that must be adopted first before the next invention can be taken.
Some inventions also have additional requirements, such as requiring a primary or integrated culture of a specific culture group, a certain government type, a certain country rank, particular DLCs, or simply only being available to certain countries. These culture-, government-, tag-, rank-, and DLC-specific inventions generally will not appear unless their requirements are met.
Most inventions have modifiers that are applied when active, which are permanent modifiers that the country gains once it adopts the invention. Some inventions also have when activated effects, with some merely descriptions of buildings, wonder effects, subject types, or other mechanics that are permanently unlocked once the invention is adopted, while others are one-time effects and bonuses that triggered immediately when the invention is purchased. Some inventions are keystone inventions that are specially marked with a more elaborate border; these mark inventions that are considered important, whether because they have a strong effect or modifier or unlock particularly important mechanics, but are not mechanically different in any way from normal inventions.
Unlike advances, no country has any inventions adopted at the start. However, most countries that start with a higher level of advances do start with a corresponding number of innovations to purchase inventions with at the beginning of the game.
Each invention requires spending one innovation to adopt. Innovations are gained primarily from technological advances, which grant one innovation for each level, and can also be gained by adopting certain military traditions, as a reward for certain specific missions, as a rare outcome of successfully stealing technology, or occasionally from researchers that have certain traits. All innovations are equal, and there is no requirement to use innovations gained from a particular field of advances on an invention inside that field. It is entirely possible to invest all of a country's innovations on a single field of inventions, if the country is willing to neglect the others. Note that there are many more inventions than it is realistically possible to adopt over the course of the game, and even technologically advanced countries will be forced to pick and choose which areas they want to prioritize and which inventions they will leave for later - or not at all.
- +4 from The Bureaucracy of War (Indian traditions; under Indian kingdom traditions)
- +4 from Cradle of Civilization (Levantine traditions; under Levantine kingdom traditions)
- +4 from Cavalry Skirmish (Persian traditions; under Persian rural traditions)
- +3 from The Fabri (Italic traditions; under Roman traditions)
- +3 from Roman Roads (Italic traditions; under Roman traditions)
Every researcher that has at least one of the obsessive, intelligent, polymath, or scholar traits has a chance generating an extra innovation each month (as well as gaining 5 statesmanship). The base chance for each researcher is around 0.2%, multiplied by around 1.25 for each trait that the character has. Since a researcher needs at least one of the traits to be eligible for generating extra innovations at all, the effective base chance is around 0.25% for a research that has one trait, going up to a maximum chance of around 0.49% per month for a researcher that has all 4 traits. This chance is rolled for all researchers that are eligible, so having multiple researchers that have at least one of these traits significantly increases the chances of getting an extra innovation.
Once a researcher discovers an extra innovation, there is a cooldown of 2 years before the country can get another free innovation, and a cooldown of 5 years before that particular researcher can generate another free innovation (however, during the intervening 3 years other researchers can still generate free innovations).
Lists of inventions