Here is the full list of all 16 Graveyard Shift achievements.
Complete game in normal mode
Complete game in easy mode
Collect 1000 mushrooms
Score a 10000
Kill 500 ghosts
Score a 1000
Score a 100
Complete game in hard mode
Throw 500 mushrooms
Kill 250 ghosts
Collect 500 mushrooms
Throw 100 mushrooms
Kill 100 ghosts
Collect 250 mushrooms
Kill three ghosts with one mushroom