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.
Successfully launch the game
Completed ACT 1
Completed ACT 2
Completed ACT 3
Found the Act 2 Easter Egg
Found the Act 1 Easter Egg
Found the Act 3 Easter Egg
Pick up 100 cases
Pet the dog