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