This is a free, touchscreen version of my Stargazer MIDI controller.

The default layout for this keyboard is chromatic, arranged like a bass guitar. Steps to the right increase by 1 semitone and steps up increase by 5 semitones. You can change the keyboard’s size and intervals from the Settings panel.

The closest thing to this that I know of is the Linnstrument, which is out of my price range but looks brilliant. Keyboards like this are sometimes referred to as “isomorphic” or ‘‘2-D”.

Check out the hardware controller in action here: https://youtu.be/ytyOffQuA5o