Crusader Kings 2: The Old Gods release date and new details from Monday's livestream

Sharpen your old axes: Crusader Kings II's pagan/viking expansion, The Old Gods, has been confirmed for a May 28 release. Alongside the announcement, a two-hour livestream on Monday unveiled some new details, as well as a few things that have been added since the last live build we had a look at. I've tried not to retread too much previously released info, so if you need to get caught up, here are my breakdowns of Dev Diary 1 , Dev Diary 2 , and Dev Diary 3 . You'll find the freshest bits below.

What we learned from the livestream:

The only republics existing at the 867 A.D. bookmark are Venice and Amalfi, the latter being a completely new historical trade union made up of both Italian Catholic and Greek Orthodox patrician families. Genoa and Pisa can both form between 867 and 1066—we saw Genoa pop up during the stream. We're unsure whether or not they always will.
According to game designer Chris King, there is a new "Berserker" trait that certain characters can have. The effects and cultural restrictions remain unknown.
Since there weren't that many powerful Shiite Muslim landowners in 867, an event will fire after game start that spawns the first Shia Caliph. He will begin as a landless adventurer with a large host of supporters, and carve out a kingdom for himself to begin the Shia rise to power. This event was modeled after the rise of the Mamluks.
Muslims are given an across-the-board starting boost to technology, due to their historical scientific superiority during the time period the expansion depicts.
If you have researched too far ahead in any technology track, you will take a percentage penalty to researching the next step until time has caught up to the point at which that tech would have, historically, become available. Thus, rushing down one tech path will now result in less efficient use of tech points over a long campaign.
You now get a base boost to Military, Economy, and Cultural tech based on the stats of your Marshal, Steward, and Court Chaplain, respectively. Council missions no longer increase your chances of discovering new tech, but rather speed up the spread of tech in the targeted province from all adjacent, higher-tech provinces. This will give you more incentive to actually move your tech research missions around, creating "highways" of tech spread to outlying areas of your realm.
Any time you capture a fortress as any religion, you will now be able to take prisoners from the court there, such as the ruling lord's family. If you are a pagan ruler, you can force any such prisoners who are female and of age to become your concubines.
Succession for pagans treats children of concubines exactly the same as children of wives.
Zoroastrian rulers are apparently less concerned with incest than other religions. Concrete details were lacking, but they made it sound like marrying your own daughter is all well and good with Ahura Mazda.
The Jomsvikings are in the game as a Holy Order that can be hired by Norse Pagan rulers. Holy Orders for other pagan religions are still under consideration.
There will be a much larger mercenary pool, and many cultures that did not have cultural mercenaries will have them now.
Flavor events surrounding the great East/West schism in Christianity are still being considered, but are not currently in the game. Orthodox and Catholic are still being treated as "effectively separate" in 867.
If you are a pagan ruler under a Christian liege (such as Erik the Heathen in 1066), some of the pagan mechanics—notably raiding—will be switched off. We're unsure if this is based only on top-level liege, or if it applies to any liege. (For example, a pagan count under a Christian duke under a pagan king may or may not have these restrictions.)
Heretics can now rise up in organized rebellions.
New formable empires include Abyssinia and Mali on either side of Africa. These join the previously-revealed Tartaria, Carpathia, and Italia, such that every province on the map now belongs to a de jure empire.
Dublin will be ruled by the Norseman Ivar the Boneless, son of Ragnar Lodbrok, in 867.
Pagans have the ability to sacrifice prisoners for Presige and Piety boosts.