The Basics
This is an 8-bit/pixel graphics-style game that came into being as one of the stretch goals on the “Bloodstained: Ritual of the Night” Kickstarter. Both games are heavily-influenced by Castlevania, and both are spearheaded by former Konami exec and Castlevania creator, Koji “Iga” Igarashi. This prequel is an (intentionally) simplified game that plays much like a modernized Castlevania III, allowing the player to swap back and forth among several unlockable characters on the fly (a la CV3), while also allowing for more modern ideas like half a dozen endings, having the choice to recruit, leave behind, or even kill (!) your potential allies, as well as having character abilities that allow you to access shortcuts – whether by freezing a foe (including bosses!) and using them as a platform, smashing down an inconvenient wall that happens to be in your way, or simply flying around them.
Story & Flow
You go forth through the levels, collecting power-ups and trying not to die. Kill baddies along the way, break LOTS of candles, and then face off against a boss. The bosses pretty much cover the whole gamut, from fire-breathing train engines to blood-spewing succubi to leaping lizards and dastardly wizards. Taking down the first three will allow you the option to recruit an ally; you can, if course, choose not to do so simply by ignoring them, and you can even kill them if you're feeling particularly mean that night.
The sword-packing exorcist Zangetsu has come to a demon-filled castle with the intention of destroying it once and for all. When the game begins, he is the only usable character, but beating the first three bosses allows you to unlock three more characters. Miriam is a young woman who has had magical crystals forcibly implanted into her body by alchemists; she wields a whip and can jump much higher than the others; she is also the only character who can slide into cramped places. Alfred is an alchemist in search of arcane knowledge; he has low health and packs a small staff, but wields game-changing magic. Gebel is another crystal-infused human who has his own agenda; he attacks with flurries of tiny bats, and his only special power is the ability to briefly turn into a flying bat.
Graphics & Sound
A solid example of the modernized 8-bit style – Intentionally limited color palette (especially on the 4 playable characters – they're basically orange, blue, yellow, and black), with similar limitations on enemies, just without all the flicker. Highly-detailed backdrops and environs, considering, though. Rain and weather effects appear which would simply have been impossible to implement on 8-bit systems without significant slowdown/flicker, but which work just fine in this game.
Music is predominantly simplified remixes of the soundtrack of Ritual of the Night, its progenitor. It's a good place to start from, and they make for a great final aural product.