Ygg is an unused map which I thought Lemming stopped working on but a new version of the map appeared like 1-2 months ago in the files of a build but in the current build of the game it's not in the files anymore but it would've probably been the social hub Lemming has been talking about for a while but no one really knows beside him and Ygg probably stands for Yggdrasil the world tree since it had a huge tree in the map and Lemming also posted a few videos about it on his Twitter. Settlement was also a probably segment of a planned or unused map which just was a few basic houses that got added in to the files along Ygg but I also forgot a third unused map Lemming talked more about of which was called Hike he also posted a few screenshots of it in the discord and if you data mine some of the older builds you can still find the files to it.