The Kundalini Piano Mirror is a program for real-time transposition (remapping) of midi messages that is designed for use with a standard midi piano keyboard to facilitate playing using symmetrical inversion.
The remapping performed results in changing which pitches are produced from which notes on the piano keyboard, making novel ways of playing the keyboard possible.
Specifically, the Piano Mirror software makes it possible to either mirror left-handed passages into the right hand, mirror right-handed passages into the left hand, or to completely reverse the keyboard such that the left hand plays the original right-hand part in mirror image, while the left hand simultaneously plays the original right-hand part in mirror image.
A more complete explanation can be found at:
https://www.kundalinisoftware.com/kundalini-piano-mirror/
(Please note that this software requires some way to plug your digital piano into your keyboard, probably using a USB 2.0 Micro to A Female adapter coupled to a a MIDI to USB cable.)
Source code available on Github:
https://github.com/BenjaminPritchard/PianoMirrorGooglePlay