Welcome to another developer diary for EU4. This time its about country customization - our efforts to make each country truly unique.We added National Ideas as a feature to the series in EU3. It was a great concept, because of how it added visible differentiation to countries, and we were really happy with the results. In EU4, we have revitalized the idea system to more properly represent the differences between countries. Our new design for ideas is something that should be satisfactory to the historical crowd and to those who prefer more of an open-ended game.Instead of choosing national ideas when various techs are gained, you now have slots for idea groups. Idea groups consist of seven ideas and have a bonus for getting all of the ideas in a group. Picking ideas within a group has to be done sequentially – you can't leapfrog from an early idea in a group to a later one, but you can choose from any available group at any time. You are not forced to buy all ideas in one group before getting ideas from another group.You have eight possible slots for ideagroups, which is given from various technlogy levels. What makes the game more interesting though, is that when you have selected an ideagroup, you are basically stuck with it. You have chosen the path for your nation. Investing into a full idea group takes quite a while, and can cost several decades worth of power.There are sixteen possible idea groups you can choose from in EU4, each with seven different ideas in them, and a bonus. They are Plutocracy, Aristocracy, Innovativeness, Religion, Espionage, Diplomatic, Offensive, Defensive, Trade, Economic, Exploration, Naval, Quality, Quantity, Expansion & Administrative. Remember – you can only have a maximum of eight of these, so half of the idea groups will never come into play for your country. You veteran players may notice how many of these idea groups parallel the tracks that used to be domestic policy sliders.Each of these idea groups use one specific monarch power for buying ideas., To increase in offensive ideas you will be using military power and exploration uses diplomatic power, for example.Every country also has something we call National Ideas, with the most important countries having a set of unique national ideas. Major countries including the Mamelukes and England have seven unique ideas granting them specific abilities. These ideas are not something you spend power on to buy, but, instead, you gain one of these ideas for free for every third idea you buy normally from an idea group.Every nation also starts with a national tradition: two abilities which define the history and heritage of the country. As we see here, Sweden starts with 5% better infantry and 25% cheaper mercenaries. Countries also have what we call “national ambition”, which is a bonus given when you have gained all seven of your national ideas. This bonus is also unique for each country.To make the game more comprehensible and transparent, ideas are represented by icons that correspond to their effects.Every time this effect is active or needed for display purposes (like in describing country modifiers or religious bonuses) you will see this icon. That way you can tell at a glance the impact your ideas are having on your national evolution.Next week, we'll be back to talk more about .. lets see… something on the isles..