The initial story of the game follows a werewolf named Cornell who enters the castle eight years prior to the events of the original game to rescue his sister Ada; he also finds and liberates a boy named Henry Oldrey, who grows up to become a soldier for the church who — wait for it — enters Dracula's castle, only his mission is to rescue children there.
Reinhardt and Carrie, the original heroes of Castlevania 64, become playable after completing the game once. See the page for tropes describing their adventures.
Legacy of Darkness provides additional examples of:
- And Your Reward Is Clothes: The unlockable alternate outfits let you scoff at the redesigns by playing in characters' original Cv64 oufits, including Cornell's.
- The Bad Guy Wins: Since Cornell's story is a prequel, the bad guys win and set in motion the events for the original Castlevania 64.
- Broad Strokes: Reinhardt and Carrie's games travel through Cornell's variations of the levels and omit lines of dialogue they had in the original, so there's still some merit in owning both games if you want the whole story.
- Cores-and-Turrets Boss: The "Crystal Laser of Doom" in the Tower of Science, which consists of a large, central crystal and several self-repairing turrets of various types placed around it.
- Embedded Precursor: Completing the game as Cornell unlocks the story modes of Carrie and Reinhardt, the original heroes of Castlevania 64.
- Fan Disservice: One of the Spider Queen's attacks is to reel in your character with web and chew on him/her with her second mouth. The one that's right at crotch-height on her, latches onto him/her at waist-height, and is complete with thrusting movements.
- Fur Against Fang: The game fits this trope nicely. It not only has a higher than usual number of vampires, but lead character Cornell is a werewolf.
- Harping on About Harpies: A harpy appears as a boss in Cornell's story.
- Historical Villain Upgrade: The servant posing as Dracula from the original release is revealed to be noted 15th century soldier and child killer Gilles de Rais, now a vampire and servant of Dracula.
- King Mook: One of the new bosses is Spider Queen, leader of the underground Spider People.
- Nice Job Breaking It, Hero!: Cornell tries to rescue his sister, it leads to Dracula getting resurrected early by being born as Malus.
- Multiple Endings: Playing as Henry, the endings depend on how many children you rescue.
- Our Werebeasts Are Different: Cornell is a werewolf, and his rival Ortega becomes a werechimera thanks to Dracula's borrowed power.
- The Resenter: Ortega, Cornell's rival, who envied Cornell's mastery of his alternate form and sought Dracula's help to match him.
- Schizo Tech:
- Henry wields a revolver as his primary weapon, which can be reloaded with cartridges. While revolvers did exist during the time period in which his story takes place (1852), cartridge rounds did not, only coming into existence four years later.
- The armor Henry wears along with the armor that is on Reinhardt's alternate costume are several centuries out of date.
- Shock and Awe: The Vampire Killer's final powerup grants it lightning properties in Legacy of Darkness; this replaced the fire effect from 64.
- Super Mode: Cornell's werewolf form enhances his strength.
- Tears from a Stone: A statue of Virgin Mary appears, which weeps Tears of Blood.
- Took a Level in Badass: Henry is first met in Cornell's storyline as a helpless young boy who must be escorted out of the premises to safety. His storyline sees him grown up into a tough-as-nails knight armed with a flintlock gun who goes back to Dracula's castle to save a group of children kidnapped by his followers.
- Unlockable Content: With each child Henry frees, a new option is made available to the player.
- Updated Re-release: Though it would be better to call the game a complete version of the original release.
- Walking Shirtless Scene: Part of Cornell's outfit is an open shirt, and he loses it completely in his werewolf form.
- The X of Y: The new subtitle.