So with OKCupid, the engine of it was the question system. An example,
Star Trek
Star Wars
Neither
Both
You put your answer, but there's more.
You could set what
range of answers you would accept, and you could
personally weight the importance of their answer from "not at all important" to "this is a dealbreaker".
So if you're a stan for Star Wars, and wanted to filter anybody else but true believers out. You only accept that, and set it to dealbreaker.
If you wanted to generally match for someone who was a sci-fi fan, you'd make everything but neither acceptable, and set it as somewhat important.
If you think sci-fi/fiction is a dumb waste of time, you set neither and make it very important or a dealbreaker.
If you have literally just don't care, you just answer and set it as not important.
And there would be questions for all sorts of stuff, entertainment, hobbies, values, ethics, politics, fetishes, etc.
It was an amazing, nuanced system. You could find great matches on your own, and their backend math just made it better.
And Match gutted it to turn OKC into it's Tinder competitor.
You could also be up front if you were looking for a long or short term relationship, or just casual sex.