Netflix has dozens upon dozens of hidden genre codes that you can enter manually in your browser to search not just for Horror movies for example but B-Horror Movies (8195) or Cult Horror Movies (10944) or Deep Sea Horror Movies (45028).
If you would prefer to peruse a list of these narrow genre categories right from within Netflix instead of typing them into your browser's URL bar, then you need the Netflix Super Browse extension. It's available for Chrome and for Firefox.
Netflix Super Browse adds a Super Browse header to the left of the Browse header at the top of Netflix. Hover over Super Browse and you'll get a drop-down menu of these subcategories listed alphabetically.
The extension doesn't replace any of Netflix's regular search tools but adds another tool if you are in the mood for something specific. The list is long but scrolls easily.
Netflix Super Browse may become my go-to Netflix search option, particularly as I become more familiar with its long list of categories.