Korea is coming to Civilization 6, led by the formidable Queen Seondeok, the first Queen of Silla, which along with Baekje and Goguryeo made up the Three Kingdoms of Korea. As described by Wikipedia, Queen Seondeok's reign was not without its problems, including wars with with Baekje and Goguryeo and an uprising led by men who believed that women aren't fit to rule. But she reigned for 15 years, during which she put welfare policies into place, invested heavily in education, and is credited with encouraging "a renaissance in thought, literature, and the arts."
Korea's unique district in Civ 6 is the Seowon, an upgrade to the Campus, which provides a fixed yield of science. That yield is reduced by districts built next to it, but Korea's unique ability, Three Kingdoms, grants bonus science to mines, and bonus food to farms, that are built adjacent to Seowon—an interesting (and worthwhile) tradeoff.
The Hwacha unique unit is a mobile ballista mounted on a two-wheeled cart that's capable of rapidly launching 100 rocket arrows, or 200 Chongtong bullets, against distant targets. It's "much more powerful than its Renaissance-era counterparts," and enabled a small number of Korean defenders to repel an invading Japanese force of nearly ten times its size in the Battle of Haengju in 1593.
The in-game queen reflects her real-life counterpart with the Hwarang unique ability, which grants bonuses to science and culture in all cities with an established governor.
Details about the coming Korean civ are up at civilization.com. Korea will be added to Civilization 6 in the big Rise and Fall expansion that's coming on February 8. Here's everything we know about it so far.