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