Here is the full list of all 18 Mundaun achievements.
Don't leave Mundaun
Drink all of the coffee
Draw all the maps
Show the Mountain Prisoner book to HR buried in the snow
Turn on the chair lift
Pick up rifle
Win the sleigh race
Find the waterfall cave
Use one of the transport furniculars
Fill the Muvel with hay
Drive the Muvel
Find Jeremias's key
Find the cave in the first area
Finish the game without hurting an enemy
Finish the game without dying
Scare off the bees with smoke
Leave Mundaun as you came
Leave Mundaun changed