There's also a new naval system with "greater detail in battles," like range of guns etc along with more ship types. We also get international crisis and a newspaper system to 'filter' out events.
Apparently the Great Powers will also be able to colonize areas previously inaccessible, which means there'll be a lot more Africa to cherry pick.
"Rapid industrialization and new technologies have made it possible for your growing power to push into lands once considered uninhabitable for “civilized” men," reads the Paradox press release. "The riches of Africa beckon you, as you explore new territories and exploit the wealth and people within. But a growing empire will eventually bump into another power with the same ambitions, and a savvy smaller state will know how to exploit the conquerors’ greed and pride."
"Heart of Darkness", as its name suggests, focuses on the Scramble for Africa, the late 19th century rush for newly discovered wealth and land in a continent whose interior had been mostly free from European domination."
International Crises are the new diplomatic events where rival empires can seek out Great Power mediation to settle an issue, which can of course be manipulated by the minor powers if played right.
Heart of Darkness highlights:
■ Experience a brand new colonization system
Use your navy to expand your empire, compete against other colonial powers and struggle to maintain your overseas control. Colonial conflicts can spiral out of control and become international crises where they will have to be decided by diplomatic negotiations or risk costly wars.
■ Battle your enemies in the new naval combat system
Together with the new colonization system, your navies are more important than ever. We have revamped the entire naval combat system and made it much more detailed and exciting with a new system of gun ranges and maneuvering into positions for battles. New powerful battleships join the other classes of ships to bridge the gap to Dreadnoughts.
■ Prepare for International Crises
Around the world international crises continually call on the Great Powers to mediate and compromise, with war always being the last resort. As one of the lesser powers, use your influence to stir up the local flash points so you can use fleet footed diplomacy to get the Great Powers to right the wrongs that have been committed against your nation!
■ Follow the global events with the new newspaper system
You will receive reports on local and global events as well as the world's changing situation to keep up to date and get a greater sense of immersion. Over 60 newspapers, both historic and otherwise, periodically present you with the latest news reports of war, major events, royal gossip and other matters of interest.
Victoria II: Heart of Darkness releases on PC in March 2013.