Kaesong

Kaesong is a lost level that was supposed to be in the Korean campaign in Age of Empires II HD: The Forgotten but was dropped out of released due to to time constraints

Even thought it was dropped before the final release, it can be downloaded on this page.

Take the place of a famous Korean general and reunite Korea once more. This scenario is a build & destroy scenario where you face several enemies. Are you able to turn the tide and bring your people victory? - Short explanation from the creators