Here is the full list of all 19 Spooky Bonus achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Purchase all of the house decorations.
Purchase the Grey Alien decoration.
Beat the game in Timed mode.
Beat the game in Relaxed mode.
Reach the Crypt.
Set off a Garlic Bomb
Upgrade a powerup to level 3.
Use all 6 powerups on a single level.
Collect 10 coins on a single level.
Score 8000 in a single level.
Reach the Asylum level.
Reach the Dungeon level.
Find a black cat.
Collect a bag of coins.
Score 5000 in a single level.
Set off 20 bonuses on a single level.
Chain react 6 bonuses at once.
Chain react 3 bonuses at once.
Match 5 shapes at once.