Following up on one of the greatest games of all time... On 2007 mobile phone technology.

When the first Castlevania released for the Famicom Disk System in 1986, it was a uniquely-themed, but fairly conventional 2D platformer. However, in 1997, the PlayStation title Castlevania: Symphony of the Night not only catapulted the franchise forward in terms of gameplay originality, but also inspired the classification of the Metroidvania genre we know and love today.
It's really no surprise then that the game received six beloved direct sequels on Nintendo handheld systems – but also one on 2000s mobile phones, which Konami desperately wants you to forget about.
Trading Whips For Magic
Castlevania: Symphony of the Night and its successors heavily deviated from the gameplay formula established by previous Castlevania titles: While still 2D platformers, the main goal changed from reaching the end of several distinct levels to just having one giant level – Dracula's castle – to explore.
Mainly, however, the introduction of experience points, power-ups and new abilities that needed to be unlocked in order to reach previously inaccessible locations completely changed how players approached the game and made it perfect for handheld play, thus explaining the six Game Boy Advance and Nintendo DS sequels.
So, when it came time for Konami to underscore "its commitment to the mobile games market [...] by announcing the development of original content specifically for mobile phones", to quote an official press release, it only seemed logical for the company's US-American branch to do so with a Castlevania game, leading to the release of Castlevania: Order of Shadows in 2007.
Backtracking To Old Structures (With New Abilities)
It's important to keep in mind that the J2ME-compatible devices and Windows Phone on which the game was released aren't really comparable to modern smartphones. They were technically vastly inferior to even the Game Boy Advance, forcing some concessions during development.
Castlevania: Order of Shadows (not to be confused with the similarly-titled 2008 DS game Order of Ecclesia) retains gameplay mechanics of the Metroidvania titles such as experience points, level-ups, sub-weapons and spells, but recontextualizes them by mixing them with the whip-swinging and level-by-level structure instead of one interconnected open world from older Castlevania titles.
This unique gameplay blend is supplemented by an original soundtrack and a plot that sees Desmond Belmont take on a sect of demon worshipers known as the Order, who seek to resurrect Count Dracula in order to please the Dark Lord, hoping to be rewarded with eternal life. Instead of a castle, they reside in a mansion, making the setting at least somewhat original.
Disowning A Cursed Child

While Castlevania: Order of Shadows is certainly interesting in its premise, the technical constraints of its hardware limited the game's performance, length and difficulty, effectively making it worse than the all other Castlevania Metroidvanias by default.
Not only that: The game – as a side story – is fairly disconnected from the other titles, not even being part of the official Castlevania timeline. The developers being part of the US-American Konami Mobile division instead of the usual Castlevania studios (with a different developer being typical for forgotten & neglected sequels), plus the game never even releasing in Castlevania's home country of Japan further made it prime material to become the disowned child of the series.
The game originally wasn't even supposed to star a Belmont, with the story originally centered around the completely new LaRue family of mages. In the end, while the other Symphony of the Night sequels got re-released in the Castlevania Advance Collection (2021) and Castlevania Dominus Collection (2024), Order of Shadows remains stuck on 2007 mobile phones.
Resurrecting The Dead
... Unless you boot it up through an emulator, that is. Although J2ME emulators are notoriously prone to crashing and sound bugs, they allow you to freely set the aspect ratio and use inputs other than tiny mobile phone keys, vastly improving Order of Shadows' playability.
While there are no mods for the game itself, its setting and characters have been brought to other games by fans, such as via Castlevania: Portrait of Ruin Desmond hack in April 2012 by Pemburu Vampir. Modder VVizard has developed several stages inspired by the franchise to platform fighter Rivals of Aether, including one named Daring Assault based on Order of Shadows in March 2020.
If you're looking for an entirely fan-made experience, the unofficial, open-source crossover fighting game Castlevania Fighter, based on the MUGEN engine, has been graced with the presence of Desmond Belmont as a playable character in 2023. But will Konami will ever let us play as the vampire hunter in any official capacity? It seems only time will tell...