This is one of the songs from the album Vampire Variations, which is a tribute to the Castlevania game series. The album is a collaborative effort between many different artists, in celebration of the series' 25th anniversary. Each artist got to choose one or two songs from the series to record, resulting in twenty amazing and varied covers and adaptions of classic Castlevania tunes. Some very talented and successful game cover artists, like my personal favorite, Stemage from Metroid Metal, are a part of it. You can download the album for free from the project's website.
Last year, a very similar album was done for the Metroid series. The album, known as Harmony of A Hunter, did the same practice of having different musicians sign up to record one or two tracks each. That album is equally amazing, (I actually think it's better and far more varied) and can also be downloaded for free right here. Harmony Of A Hunter was the first totally independent tribute album to be made for a game series' anniversary, and it looks like it might have started a trend. Hopefully we'll see these tribute albums for many other game series, as well.