I really enjoyed the Stockfighter levels too, and reading The Big Short / Flash Boys / Moneyball in preparation. The levels had the right level of difficulty & I kept feeling I levelled up (especially when optimizing levels, I'm still proud of my Level 5 score). I didn't enjoy the AVR levels the same way & bailed quickly on those.
I got spooked after someone posted on HN that their Starfighter referral had only bypassed the CV screen of the job interview, not programming or whiteboard challenges. That made me question the time I'd spent on Starfighter - I kept a time log in Harvest along the way, and it's about the same amount of time I'd spend on developing a new product to sell online.
I still enjoyed playing Stockfighter though, and it helped me sharpen my Golang skills.
In other words, maybe it turned out to be a better filter for self-starters who might be nascent entrepreneurs (reflecting the founders who created it), but sometimes those characteristics aren't what hiring companies are looking for when they have a specific role to fill.
Sometimes you interview people who would be outstanding in certain roles or for certain companies--but maybe not the one you happen to be currently working for.
I'm struggling here, but FizzBuzz is effective as a tool to weed people out, but FizzBuzz taken to the extreme doesn't necessarily equate to a tool to rule people in.
I also really enjoyed stockfighter challenges. Between those six and my university's copy of Harris' Trading and Exchanges, I learned quite a bit. I bailed out on the AVR challenges though.
From a purely selfish viewpoint, I also want to work at places where the hiring process isn't really just whiteboard or gotcha questions, but instead actually has some consideration that, you know, demonstrating the ability to produce working useful code matters. Maybe I'm just nuts. The last interview I was in (for what people here would say is data science/engineering) involved a couple of big-O questions and two ill-specified SQL queries . . . sigh.