Here is the full list of all 26 Don't open the doors! achievements.
Beat all the doors.
Explode the main door.
Kill 1000 bugs.
Break the beetlejuice cauldron.
Kill 50 spiders.
Find all the gold keys.
Upgrade diamond armor to max.
Read all the diary parts.
Drink 200 pots of compote.
Squash 2000 objects.
Kill 50 bees.
Collect bee glue.
Don't take any reward from Mr. Bee and pass through the hive gates.
Kill 1000 flies.
Die 25 times.
Wear the glasses.
Defeat the Pumpkinello.
Defeat the Great Cactus.
Squash 100 chests.
Carry a large amount of money.
Kill 5 enemies with a single hammer srike.
Kill 20 enemies with a single hammer srike.
Find a book.
Defeat the Arik.
Kill 10 enemies with a single hammer srike.
Bring the megabomb.