On 5 March 2008, a second expansion titled 'In Nomine' was announced. It was officially released on 28 May that same year. Features include: a further extension of the game's time frame, the addition of the Byzantine Empire, a revised AI which focuses on strategic toplevel goals, and completely reworked rebellions with their own goals and abilities. Virtual Programming published the In Nomine expansion for Mac OS X on 18 August 2008. The game now starts earlier, starting in October 1399, at the coronation of Henry IV of England. Expanding the game time by 50 years, this means the game includes the Byzantine Empire, Tamerlane and the end of the Hundred Years' War.
A key variation of the expansion is the ability to make the decisions that will shape the future of the country. For instance, a player can choose to create the United Kingdom, make Paris "worth a Mass", or institute an East Indian Trade Company. They can now implement decisions on both country and province level, with the new decision system, including hundreds of different decisions depending on situation (for example state religion), and country.
There is a new mission system, where the player and AI will both be given goals to achieve, such as conquering Ireland (for England), vassalising Lorraine (for France), liberating your countrymen, or reclaiming stolen territory. In Nomine also features 'rebels with a cause'. There are countless types of rebels (Religious, Patriotic, Peasant...), with different goals, and different abilities. For example, patriot rebels mean 10 years more nationalism if they take control of a province, and are more likely to defect. You may get colonial rebels in your colonies determined to get representation or independence, you may get reactionary nobles rising up to put the serfs back where they belong. You can now choose between crushing them by force, negotiating with them, or leaving them and watching them enforce their demands on your country. Religious tolerance now depends on the ideas and decisions you take (rather than the more usual sliders), making it a new layer of strategy, although choices are few and far between. As cardinals stay loyal longer, the power of the Papal Controller has grown, as he can now excommunicate rulers, and call crusades against infidels (giving bonuses for any Catholic nation fighting them). It also features a colonial system, where there is a key metric - the distance between where you want to colonise and the nearest core port. Elections in Republics, scorched earth & new spy missions also feature.
Source: Wikipedia, "Europa Universalis III", available under the CC-BY-SA License.