As tends to be the case with a Paradox grand strategy expansion DLC release, the base game of Europa Universalis IV is getting a major patch too. When the El Dorado DLC is released tomorrow, it’ll come with a mega-patch that even people who didn’t purchase the expansion will benefit from.
You can read the full changelog in exhaustive detail over at the official Paradox forums. It’s been a while since I’ve been able to yell at Austria in Europa Universalis IV so I’m not in the best possible position to pick out which of these many, many changes might be the most important ones.
“Colonial subjects taken over by annexation will now get their new overlord’s map color instead of retaining their old overlord’s color” looks like a really good one though. That was pretty annoying.
In terms of what additional free features will be added; South and Central American countries will be getting a lot more dynamic historical events, plus the defined religions of Inti, Nahuatl and Maya (though none of the specific mechanics unique to El Dorado.) As well as that, all subject states will now have a “Liberty Desire” relative to the strength, taxation levels, war exhaustion (and so on) of their Overlord.
Once that Liberty Desire creeps over 50, the subject will stop paying taxes and contributing to wars. At 100, they’ll outright declare war of independence.
“Drylands, Steppe, Highlands and Farmlands” have been added as new terrain types too.
Again, have a read of the full thing for the complete overview of what’s going to change.