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.
Beat the game in Relaxed mode.
Beat the game in Timed mode.
Purchase all of the house decorations.
Purchase the Grey Alien decoration.
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.
Reach the Asylum level.
Chain react 6 bonuses at once.
Reach the Dungeon level.
Score 8000 in a single level.
Set off 20 bonuses on a single level.
Find a black cat.
Score 5000 in a single level.
Chain react 3 bonuses at once.
Collect a bag of coins.
Match 5 shapes at once.