Here is the full list of all 38 Halloween Forever achievements.
You won as Ms. Witch! Hope you had a feline time.
Find all six hidden runes for a secret ending!
You bested Necroking! The return of Necromancer! How the mighty have fallen.
Set loose 666 cats as Ms. Witch.
Trigger spike traps 101 times.
You rescued Ms. Witch! She has endless cats!
Run away from a crow for a very long time.
You bested Blue Devil! Necessity is the moth of invention.
You bested Frog King! I toad you so!
You bested Manleech! Say your lamprey-ers!
Wake up 6 sleepy frogs.
You bested Necromancer! Back to ghoul school with you, fool!
Knock five spiders off the wall.
You bested Eyeskuller! Eye spy with my little eye something that's about to explode!
Make Chainsaw Megamaniac leave his chainsaw behind when he dies.
You bested Red Devil! Yow, it's hot in here!
Destroy five hanging skeletons before they hit the ground.
You rescued A Skeleton! A bony vertebra buddy.
You bested Green Hydra! Two heads are better than none, but that won't slow us down.
You bested Big Bat! Have you ever seen a bat so big?
You rescued Butternut Bro! Your gourd from another lord.
You bested Chainsaw Megamaniac! There's no chainsaw maniac tougher than this one.
Destroy a breakable wall.
You won as Butternut Bro! Way to squash the opposition.
You won as A Skeleton! I knew you had it in you (I can see through your ribgaps).
Never harm little bats! Ever!
Beat a world without taking a hit.
Beat the game with 1 HP Mode enabled! HARDCORE!!!
Get grabbed by Blue Devil three times.
Watch Manleech vomit 10 times. Yucky!
You won as Pumpkin Man! Get pumped!