Looking at the mashup of delightful Disney properties with epic Final Fantasy characters, most players wouldn't expect a game like Kingdom Hearts to have a huge amount of nightmare fuel. However, the introduction of one Heartless enemy type early on, the Soldier, immediately raises the stakes for the battle against the darkness, and quickly terrifies new players who had just been primed for a light, happy romp with Kingdom Hearts' overly cheery protagonist.
When it comes down to the lore behind the Kingdom Hearts' primary cannon fodder throughout the game, the true source of the Heartless is already disturbing enough on their own. Being the "darkness given flesh" born from the darkness that resides in people's hearts is already creepy, thanks to the implication that every enemy the player faces used to be a person, and that's before looking into the history of the emblemed Heartless.
Erratic and Eerily Familiar Design
One thing that stands out about the Soldier, above all other enemies in Kingdom Hearts, is the erratic way that the Heartless moves, even when just standing in place as it prepares to attack. These creatures never stop moving, and the jerking motion is unnatural and uncanny, especially when combined with the fact that this enemy is the most human, or humanoid, looking of its fellow Heartless. While it's true that some of the more common enemies in the game actually have more animations than some bosses, this goes beyond a large collection of movements to draw from and goes all the way to crafting a creepy, uncanny illusion.
On top of the unnerving animations, the basic design itself takes familiar concepts from previous Final Fantasy characters and attempts to twist it in a cartoonish style to fit alongside the Disney-themed locations. One character who still hasn't made an appearance in Kingdom Hearts, Final Fantasy 9's Steiner, has a strikingly similar design to the Soldiers' with their slanted, metal helmets and puffy, shin-high pants. Considering that one of Steiner's companions has shown up in the series, but none of the others have appeared so far, the extended implication of who's hearts may have made some of these Soldiers is as chilling as their haunting introduction.
Introduction of Emblemed Heartless
Looking beyond the design and the uncomfortable way that Soldiers move, the introduction of this specific type of Heartless is what tips the enemy over from haunting to full on nightmare fuel. In an effort to show the real stakes of the game, a Soldier is used in the only cutscene that shows how the Heartless get their name, and gives a detailed visual of the enemy stealing someone's heart and holding it within themselves. This also serves as an introduction to the emblemed Heartless, and shows the stark contrast that separates them from other, standard versions like Kingdom Hearts' early Darkness bosses.
As players learn through the first set of Ansem Reports in Kingdom Hearts, and is reiterated in 358/2 Days, the emblems that appear on most of the Heartless that players fight are more than a random design choice. These emblemed enemies were created by series antagonist Xehanort and are the only ones actually capable of capturing and collecting hearts from people, as opposed to simply killing them or transforming them into more heartless like standard Shadows do. This becomes a major plot point in Kingdom Hearts 2, with the keyblade freeing these hearts to form the giant Kingdom Hearts moon, but that still leaves what would happen to these hearts without a keyblade up in the air.
It's a lot of these smaller design decisions and this deeper lore that not every player might look into that stacks the horror onto what could otherwise be a fairly tame enemy. However, to young players, when the game first came out, a combination of their introduction and creepy design can strike the cord perfectly to dip Kingdom Hearts into chilling territory for the game's demographic.
Kingdom Hearts: Melody of Memory is set to release for PS4, Switch, and Xbox One on November 11 in Japan and November 13 worldwide.