A more streamlined sequel to Death Mark, NG is cozier by virtue of the protagonist having friends and family that get some, or significant, development and screentime. That's both to its benefit (character depth and strength) and detriment (less intense horror atmosphere).

I recommend starting with Death Mark if you just want to be scared, and can tolerate it being horny about [mostly] female bodies in those scary situations. I recommend skipping to NG if you want a horror point-and-click VN with much less of that!

Note: the Switch version is a noticeably slower gameplay experience than it was on my Vita, and is limited to four save files. I also experienced a couple of strange glitches that weren't in my Vita playthroughs. I have to say I prefer the game's performance on Vita.