Europa Universalis 3: Napoleon's Ambition or NA as fans call it, was the first of 3 expansions to get released. It introduced some much needed improvements. Napoleons Ambition adds the Napoleon scenerio which features a revolutionary France which has new abilities to wage longer wars with Europe, mostly through new events. Napoleon's Ambition adds new units that existed during that period of time, and 5 new National Idea's that can only be used during the Revolutionary period.
Europa Universalis 3 : In Nomine and Heir to the Throne require Napoleon's Ambition to work.
Trading got an overhaul, you can now auto-send merchants and let the AI do the work for you, saving you a lot of time. Countries can now create new Centres of Trade for 500 Ducats which is a great source of income if used correctly. All oversea centres of trade are now closed untill you either get them opened trough diplomacy or untill conquer the centre of trade. New westernation events were introduced and Colonial Range was added in a patch. Colonial range limits the distance from your country at which new colony's can be created, it depends on your Naval Tech and National Idea's. An improved resource view was added.
Some changes were made to the game engine in order to improve the game's performance on computers with low spec. A new War Time Interface was added, showing an overview of your ongoing war(s). New options were added at the start of the game such as historical rulers, No Inflation, low Ai Agressiveness, etc. Lots of new Random Events were added. Several countries had their colour changed to give them better representation on the map. A total of 21 new nations were added to the game, some of them historical corrections, but also nations that historically didn't exist during the timeline of the game. those nations can become independent duo to rebellions or peace settlements. It's now also possible to re-name provinces . A new modifier for combat was added; Discipline which determines the resilience of your army.