As someone who was job searching in the recent past I can tell you: these type of "alternative" interviews are perceived by job seekers as the circus master making their monkeys dance and, therefore, horribly demoralizing. Asking your candidate to do something completely unrelated to their job just because you think it reveals something about them comes off as flexing your power over someone who's trying to get their basic needs met in a sea of ghostings and AI rejections.

It has nothing to do with applicants discarding games as silly, BTW. Instead, I suggest you re-read your comment replacing online gaming with dancing and see if you'd be excited about such an interview. If your candidate is good enough to have choices they'll go to the one who respects them and their time.

Why a multiplayer game when you can do the same test in a nicer environment at a local golf course?

They are not unconventional, they were very conventional during boom. They did not lead to great working teams, they led to "mini me" teams. Teams that force employees to "work" overtime by playing games.

Because ultimately, you are not testing working abilities, you are testing whether "he a good partner for a game".