So I've covered CotND's OST, it's official variants, and some ambitious fan projects. It is the versatility of the music that has held my interest in it. But there was a special aspect to the soundtrack, a bonus feature of sorts, that had initially caught my attention. The game uses a artificial vocal accompaniment as a game mechanic, resulting in secondary versions for most tracks. This mechanic is known as "The Shopkeeper." Just to clarify, this is not a real person's voice.
The effect this accompaniment has on the soundtrack as a whole is difficult to articulate. I suspect it was conceptualized as a gimmick or novelty, but the resulting harmony can often strengthen already well-composed pieces. Not to mention the surprising amount of enjoyment that can be had in singing along.
Speaking of which, an alternate accompaniment to the Shopkeeper was later added into the game due to the efforts of an ambitious vocalist. It might take a bit more to get used to, but I've come to admire his performances (especially for Zone 3).
BTW, Daoust has covered all of CotND's Shopkeeper tracks, including the above featured Styx and Stones.
That's technically it for Crypt of the Necrodancer. But I'll have one last thing to address next week before fully moving on.