I finished the starter world and was playing the ice world (It automatically started a game there after I opened the portal in the starter world)
About 7 dwarves in, they got mostly slaughtered by a Yeti on a small hill who kept knocking them off doing damage while they did none in return and the archers all shot into the ground... I was annoyed with the base design anyway and deleted the game and started a new one except.... Ice world is locked, I can't create a new game there now....
(edited, I can't spell Unlock apparently)