Castlevania: Circle of the Moon
Although Castlevania: Symphony of the Night wasn't initially a success, it did eventually pick up its sales pace. That, coupled with fan and critical approval of the game over time gave Konami incentive to try another game in that same Metroidvania formula. The fans were begging for it, the press was wondering why Konami hadn't made another game in the same vein -- instead releasing Castlevania: Legends shortly after, and then having a new team work on Castlevania 64 (and its prequel-and-director's cut) -- so the company pull together a team to make the game that would eventually become Circle of the Moon.
Circle of the Moon (title Akumajo Dracula Circle of the Moon in Japan, translated as "Demon Castle Dracula Circle of the Moon", and known simply as Castlevania in Europe) was the next big project from KCEK after they were done with the two Castlevania 64 entries. Reportedly this was the game they'd originally wanted to make, but the company's desires to have a 3D entry (after the flak Symphony of the Night received in the West for not being 3D, only for the fans and critics to then complain about Castlevania 64 for being a departure for the series, thus proving gamers can be fickle jerks), and you can feel their passion for the project in every pixel. This is a game that lovingly takes the feel of what Symphony of the Night and marries it to the whip-wielding, hard-edged game play of the classic titles.
Set in a Carmilla's castle (not Dracula's, it should be noted), Circle of the Moon follows the story of the evil vampire sorceress, Carmilla (of course), and her plan to resurrect the Dark Lord, Dracula. To combat the forces of evil, we are introduced to new heroes in the series: the Baldwin and Graves clans. Protectors of the sacred whip, the Vampire Killer (although the game calls it the "Hunter's Whip", so maybe it is a different holy relic), these heroes head to the castle to try and defeat Dracula before he's able to fully come to power. Things don't go to plan and it's up to Nathan Graves, current holder of the whip, to explore the vast castle and eventually reach the Dark Prince as the fate of the world hands in the balance.
Although many (including the editors of this site) praised Circle of the Moon when it came out, the game was not without it's detractors. The graphics sometimes appeared a bit muddy in the game, without the smooth, flowing graphics the PlayStation was able to create; the Game Boy Advance, while a good hand-held, was never as powerful as Sony's set-top console, and in the early days of he consoles release, without a back-light, the graphics of a number of games did suffer. This led to the gorgeous graphics of the game appearing very dark and hard to see (a problem that was "fixed", for a certain definition of that term, in the next title, Castlevania: Harmony of Dissonance). Early complaints were largely focused on this... and the difficulty.
Castlevania: Symphony of the Night was designed to be an easier game, one where the players could reasonably be expected to see all parts of both of its castles (regular and inverted). Circle of the Moon, though, was made to be harder, to give players a challenge. While there were plenty of save rooms and teleporters scattered around, the enemies themselves were unforgiving. The distance between save rooms, coupled with those enemies, and the fact that portable games are expected to be more "pick up and play" meant that it could be hard to get through an area, fight the boss, limp back to a save room, and actually save your game, all before you had to stop playing or the game killed you. At times, Circle of the Moon could be punishing (especially in comparison to other Game Boy Advance titles). That said many gamers complained (and still complain) about Symphony's lack of difficulty, once again proving you can't please everyone.
The other major complaint was that, despite being a Metroidvania title, Circle of the Moon didn't play like Symphony of the Night. While it still had the same open castle, same emphasis on exploration, Circle of the Moon has a classic "Belmont" style character, a whip-wielder that seems a far cry from Alucard and his swords, shields, magic, and sassy style. You're much more limited in Circle in some respects, although critics and fans did praise the variety of the magic (once you were able to find and unlock it) via the DSS cards.
Despite its detractors, though, audiences were primed for a new Metroidvania game in the Castlevania series. After the disappointing sales of Legends, Castlevania 64, and Legacy of Darkness, Circle of the Moon was the shot in the arm the series needed, giving Castlevania it's first Million Seller (worldwide, at least) in the series in some time. This would then lead to many more Metroidvania titles in the series as Symphony co-director, Koji Igarashi, was brought in to head up the series after this.