Here is the full list of all 9 Walking Simulator achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Completed ACT 3
Found the Act 3 Easter Egg
Found the Act 2 Easter Egg
Completed ACT 2
Pick up 100 cases
Pet the dog
Completed ACT 1
Found the Act 1 Easter Egg
Successfully launch the game