Post your general ideas here! I'll start with a quick brainstorm.

Content:

• pumpkin launcher
• spooky accessories using Trinkets API
• little pumpkin mobs
• giant pumpkin boss
• carved pumpkins
• pumpkin food
• ghost
• fun aesthetics such as menu easter eggs
• new spooky ore with weapons and toolset
• candy and other small treats with buffs
• trick or treat bags for storage
• mummified zombie
• witch water
• spooky treasure chest; when clicked, it spins up into the air with a laugh and drops loot
• a graveyard dungeon that spawns in the overworld
• spooky dimension
• Mr. Skeletal who trades you spooky goods

In the spirit of helping newcomers with their first PRs, try to leave the easier ideas alone if you're already experienced.

Content:

• Bats become hostile when it's a full moon
• Rare Vampires who can only be harmed with wooden weapons
• Multiple carved pumpkin faces
• Lanterns flicker when hostile mobs are nearby
• Vampirism enchantment (steal small amount of life when killing mobs)
• Beheading enchantment (chance of mobs dropping their heads)
• Herobrine?

Content:

• Manually carvable pumpkin faces. (i.e. https://www.planetminecraft.com/mod/1710172164-forge-pumpkin-carvier/)
• Killing normal Villagers has a chance to convert them into an Illager ghost that attempts to take revenge for you killing them.
• TRUE DARKNESS
• Crappy lanterns which only light up 5 blocks away while you hold them.

Edit: I accidentally gave the wrong example for the pumpkin carving.

Content:
Right clicking a skeleton with a jack of lantern will automatically make the Skelton equip it.

On October 31st chests will become the pumpkin chest texture.

Bone golem (snow golem shape but with bone blocks)

Your wish is my order:

Add command that lists all contributors to the project (Complete names when project is released).

EDIT: Inject custom splash text on Spooktober (my Command Commit adds TimeUtil which tells you amount of days till Spooktober)

EDIT 2: Possibly soup up Witch AI for Spooky

A hunted house that spawns in spooky dimension, with illager-like mobs inside

ideas?
eclipse

ok that was a bad joke

Idea: make all normally crafted tools cursed, so you need to use a grindstone on them

awful idea: if a sword kills a mob, it becomes "bloody" and you have to clean it in a cauldron before re-using it

The bloody part is fine. Cleaning it would be way too annoying, but you could use that for interesting purposes.

Custom magic alchemy system thing?

In the magic system each biome in the dimension makes certain aspects of magic more powerful than others. Exactly which aspects depends on the biome.

Regarding True Darkness - maybe just include it? It’s tiny.

Copying it would be fine license-wise (and I don’t care) but copy might not play nice with itself if also loaded as separate mod.