The Frozen Hearth Add-on for Nobody Saves the World has 7 achievements worth 180 gamerscore.
Earn all 36 Medals in the Colosseum and talk to The Dueling Faces
Hidden
Be crowned the True Being
Reach S-Rank on the Killer Bee
Reach S-Rank on the Mechanic
Unlock the Killer Bee form
Unlock the Mechanic form