Note: The storyline from Castlevania: Circle of the Moon has been retroactively removed from series canon.
The year is 1830. At an old Austrian castle, the worshipers of Chaos attempted to revive the Lord of Darkness, Count Dracula. Vampire Hunter Morris Baldwin and his apprentices, Nathan Graves and Hugh Baldwin, heard of this and headed to Castlevania to stop Count Dracula's resurrection and restoration of power. However, they arrived a few seconds too late and Camilla, a minion of Count Dracula, started the rite to revive her master.
The gameplay in Circle of the Moon is similar to that of other post-Symphony of the Night Castlevania titles, in which the player must explore a gigantic castle filled with undead enemies and evil aberrations in a non-linear fashion. Generic enemies defeated by the player drop useful items and equipment, and also provide Experience points which increase the player character's power. Boss enemies provide plot progression, and their defeat allows the player to acquire new abilities such as a double-jump with which to progress further in the game, the only downside in boss battles is that Magic Crystals do not appear to replenish the player's HP and MP after the fight.