The Keyhole in this world is hidden underneath Oogie Boogie's manor.
According to the BradyGame's Kingdom Hearts II official strategy guide, Halloween Town was added again simply because of the overwhelming fanbase.
 Settings and areas
Based on the holiday of Halloween, Halloween Town is in a constant state of night. The main light comes from the bright full moon overhead. The theme for the area is a twisted, Gothic, and creepy appearance.
Guillotine Plaza (called Town Square in Kingdom Hearts II) is named after the deadly guillotine in the middle of the area. There is also a fountain full of green water and various ledges to climb on. In Kingdom Hearts II, the area takes on a slightly different appearance, the fountain now squirts water that deals damage if hit, the guillotine can come down on characters for damage if they pass beneath it, one of the gates (with presents behind it) deals damage if Sora and company come near it, and nearby grates spew poisonous gas. In both games, the Square links directly to Dr. Finkelstein's Lab, where much of the exposition for both games is initially given. In Kingdom Hearts, it also links to Guillotine Gate (called Halloween Town Entrance in Kingdom Hearts 358/2 Days), which serves as the entrance to Halloween Town.
Nearby there is a Graveyard that serves as a connection to the other places in both games. In Kingdom Hearts II, the gravestones can be knocked over for Drive Orbs and damage. In both games, the Graveyard leads to Moonlight Hill (called Curly Hill in Kingdom Hearts II); with a sundae swirl hill that can uncurl in Kingdom Hearts to take the party to the next area. In Kingdom Hearts II, the left fork in the Graveyard also takes the party to the Hinterlands, a quiet wood that leads to the trees carved with various symbols of other holidays. They in fact lead to towns of varying holidays - Christmas, Easter, St. Patrick's Day, Thanksgiving, Independence Day, and Valentine's Day.
In Kingdom Hearts, traveling over Moonlight Hill takes the party to the Bridge leading to Oogie's Manor and the Evil Playroom within that serves as the hideout of Lock, Shock, and Barrel, as well as Oogie Boogie's own Torture Chamber.
In Kingdom Hearts II, the Hinterlands will take characters to Yuletide Hill, which they can travel down the Candy Cane Lane to reach Christmas Town. In Christmas Town, characters can visit with Santa Claus himself in Santa's House and explore the Shipping & Receiving and Wrapping Rooms of the Toy Factory. Late in the game, characters can also go by Christmas Tree Plaza to fight a boss battle.
When entering the Christmas Town portal there are five other holiday doors that can be seen outside of the portal: the door marked with a four-leaved clover represents St. Patrick's Day, the Easter egg represents Easter, the heart symbol represents Valentine's Day, the turkey represents Thanksgiving, and the firework represents Independence Day.
 Kingdom Hearts
Sora, Donald, and Goofy arrive in Halloween Town and notice several Heartless immobile. They soon spot their true purpose after watching them introduce Jack Skellington. However, the Pumpkin King is not pleased with the results and decides to consult Dr. Finklestein in an effort to make the Heartless even more terrifying. Sora, Donald, and Goofy follow him and watch as the two discuss a way to fit Jack's needs. They decide to give the Heartless a heart, but their first attempt fails to work. The doctor sends Jack to find Sally and the Mayor, as they have the missing ingredients. As they are searching for the ingredients, Lock, Shock, and Barrel learn about their plans and inform Oogie Boogie. The villain orders his henchman to steal the artifical heart, which they promptly do after the group return. Jack sends his ghost dog, Zero, to follow them and they, in turn, pursue the spirit. Their hunt leads them to Oogie Boogie's Manor where they defeat the theives, but Oogie is nowhere to be found. They search the Torture Chamber, hidden underneath the manor, and find the villain, who devours the experiment in a bid to control the Heartless. Due to the artifical state of the heart, not many Heartless answer the call and, in a fit of rage, Oogie Boogie attacks. The group prevail in defeating him before departing the manor. However, Oogie Boogie fuses with his manor to extract revenge. He is defeated once more by the combined powers of Sora, Donald, Goofy, and Jack. Returning to the lab, Jack decides to cancel the Heartless Halloween festival and invites Sora to return next year.
 Kingdom Hearts: Chain of Memories
 Kingdom Hearts 358/2 Days
During Roxas's first mission to Halloween Town, he finds Jack Skellington pondering on how to make Halloween scarier and more shocking than ever before. Roxas leaves him there to think, and continues on his mission of collecting hearts. On Roxas's next few missions to Halloween Town he finds there are fewer and fewer Heartless, making heart collecting more difficult. Roxas uses Zero, who is able to locate hidden Heartless, to help him finish his mission. After a few more visits to Halloween Town, Roxas grows tired of Lock, Shock, and Barrel, who had been playing tricks on him, and attempts to stop them. They attack him, but Roxas defeats them, and they promise not to play tricks on him anymore.
Barrel almost divulges information on what they've been doing, but Lock quiets him and they escape. Disregarding their promise, the three play the same trick on Roxas immediately on his next arrival. After completing his mission, Roxas tries to leave, but is attacked by a Tentaclaw. He defeats it and returns. The Organization reports that the Heartless population in Halloween Town is unusually low, so Roxas is sent to investigate. When he arrives at Guillotine Plaza, a Heartless appears, fleeing from something. Another Tentaclaw sprouts from the ground and swallows the Heartless, a Creepworm. Roxas searches for the source outside of town and sees Lock, Shock, and Barrel escaping over the wall to Boogie's home.
He defeats the Tentaclaws at Curly Hill, before taking on the source of the cannibalistic appendages, the Leechgrave. However, Jack - watching from outside the zone of battle - likes the idea of a Halloween with "a black cloak and black tentacles". On his last mission to Halloween Town, Roxas is shown to be worrying about Xion. He resolves to finish his mission as quickly as possible and return to the castle to speak with her. As he searches through Halloween Town, Roxas is unable to find any Heartless. He decides to check outside of town, and encounters what he believes is an Orcus. The Heartless proves hard to handle, but Axel arrives and intervenes between the two. Axel reveals the Orcus as Xion, explaining that the battle was a trap to get the two to fight to the death, disposing of the weakest one. They leave for Twilight Town, disturbed by the Organization's intentions.
Sometime later, Roxas is transported here by Xion at the Manor Ruins. Xion uses the Organization's device to summon a sword to attack Roxas. However, Roxas manages to destroy the sword. Xion then transports herself and Roxas to Agrabah to continue the fight.
 Kingdom Hearts II
When Sora, Donald, and Goofy return to Halloween Town, they find Jack trying to take Santa's place. While at the same time, Maleficent has revived Oogie Boogie (although suffering from amnesia), and has him remake Santa's present-making machine into a Heartless-making machine. Maleficent has Lock, Shock, and Barrel assist Oogie, even letting them use a fearsome Heartless. Sora, Donald, and Goofy try to stop Jack's scheme, while trying to shut down the Heartless operation.
On their second visit, Sora, Donald, and Goofy learn from Jack that Christmas presents are being stolen, and resolve to find out who and to what end, the quartet visit Santa to request making Dummy Presents to draw out the thief, they end up hiding in a huge box (accompanied by some humorous dialogue) and surprise the thief, only to find, as Jack's realization so clearly states, "Doctor Finkelstein's Experiment did it!" A battle goes on with the raging machine, but Sora and friends come out on top, learning from Finkelstein later that the Experiment wished only to know the happiness that Christmas brings. Jack, all the while, thinks the box makes the magic, but learns from Sora that it's not about the box, paper, ribbons, or what's inside, what matters is the principle of giving. After this, Jack and Sally share a romantic moment in the snow, with Donald and Goofy comforting Sora about giving Kairi a real Christmas present, one that comes from his heart.
Sometime after Xemnas's defeat, Jack is seen discussing plans for the next Halloween with everyone in Dr. Finkelstein's lab.
 Character Design
Sora wears a black outfit quite similar to that of a vampire. His hands also have white gloves that are typical to Disney characters. He has skeletal bat wings on his back and wears a pumpkin mask on the right side of his face. His face is blackened so as to blend into the gothic atmosphere.
Donald wears mummy-like bandages that cover almost all of his body. A gap in the bandages shows that there is nothing under them. His features are darkened almost everywhere.
Goofy has the look of Frankenstein's monster, with a giant screw mirroring his hat coming out of the top of his head. His nose is recolored as a tiny jack-o-lantern, similar to Jack Skellington's faithful ghost-dog, Zero.
In Kingdom Hearts Re:Chain of Memories, when Riku visits this world in Reverse/Rebirth, he takes on a slightly darker look, such as darker skin and menacing eyes, his outfit is also slightly torn around the edges of the sleeves.
In Kingdom Hearts Re:Chain of Memories, when Riku visits this world in Reverse/Rebirth, the King takes on a slightly darker look, such as darker skin. The picture on his Friend Card also lacks a smile.