Any time I get a new handheld or controller I eventually find myself playing the PICO-8 version of Celeste through. For me, I think it's the best way to test a d-pad and how much accidental diagonals you're gonna get out of it.

This is a highly subjective subject (can flat out depend on how you use your thumb or what you want to feel) and there's much quicker ways to test it. Heck, some games you even might want easy/quick diagonals. Then it goes without saying that I am by no means whatsoever an expert or high level precision gamer. I'm old and slow. But I can beat Celeste in a sitting and by the end I have a "feel" for the d-pad I'm using and the nuances of it. Train my thumb to the particular d-pad for both precision and rolling.

Sure I could just load up Contra and press down and rock it back and forth like "Retro Game Corps" does on YouTube. Or load up any Wario Land game and try to do some precision butt-smashes. But a round of Celeste "Classic" will tell me the same info AND get me used to the nuances of working with it. Something about an upward test maybe? Dunno, it works.

It's a fun little test and I do it rarely enough that I'm always shocked to have forgotten a level/screen. It's a tight little game that I honestly enjoy far more than the one with the "story".

[Emulated/played on Anbernic RG35XX... That might need some d-pad tape modding]