I apologize. I was doing a lot of interviewing at the same time, so some things get mushed together in my head. The most challenging was the Unity project to create MicroChess. It was also thoroughly enjoyable to me.
In retrospect it was a dead-simple example of a low-pass filter; they then asked me what type of low-pass filter might do it, and I answered "comb filter," when I later found it was first-order Butterworth LPF. It still stings.
Thank you so much for the feedback on the process! I did want to let folks know we did hire three (3) folks from the speed interviewing pool - all of whom are Engineers. So the process was a bit clunky as it was this group first time with the Speed Interviewing design, but we were very happy with the results and the new employees we are on-boarding! We plan to use this design again in the near future and as before we will provide lunch and hopefully a great experience!