Here is the full list of all 22 United Penguin Kingdom: Huddle up achievements.
Request help from the king
Build a Village Hall
Build a Fishing Dock
Build a Temple
Build a Vase
Build an Ocean Garbage Collector
Build an Ice Rink
Build a Food Stand
Build a School
Build a Carousel
Build a Basic Cooler
Build a Herbs Collector
Build a Newcomer Ramp
Build a Snow Block Maker
Build a Science Hub
Build a Trawling Dock
Reach a population of 15 penguins
Complete the first tutorial
Complete the second tutorial
Complete the third tutorial
Complete a year in the penguin kingdom
Make a call for your first huddle-up!