HarpNinja was a step forward from bendometer back in the day.
I did some early “user-testing” on HarpNinja, and Paul gave me a free upgrade so I know I have it somewhere on my old Mac.
My main issue with it was that I never really understood the point. Maybe I did but it didn’t really connect with me some reason. I use a Korg CA-40 tuner for that visual confirmation sort of exercise. I think harp ninja will teach you scales in different positions and it might even teach in scale degrees as well as notes and keys. I learned a lot of that basic knowledge through drawing many diagrams of harps and writing out scales and playing arpeggios for chords in different positions and probably felt harp ninja wasn’t going to teach me anything but I think I hadn’t considered it’s potential value as a practice tool with the slot machine addiction factor.
I use Harp Ninja frequently. Esp If I'm working on a new song or lick. It can record 30 second segments for instant playback so I use that quite a bit.. Let's see I also use it to reference my harps most recently the difference between natural minor harp and harmonic minor stuff like that. I think the screen size has to be a bit bigger than a phone I think it's 5 by 7 or something along those lines. I have a couple of Korg things but they are too tiny for me though I don't which ones they are off hand.