Mortal Kobat's niche is largely people who really like the over the top gore for whatever reason, in the same way some people are horror movie gore fans. MK is

Mortal Kobat's niche is largely people who really like the over the top gore for whatever reason, in the same way some people are horror movie gore fans. MK is also one of the few Western fighting games left which have a different play style to other fighters like Street Fighter, UNIST, or Tekken which probably makes up the most of the playerbase that might fall in the less gore category.