tonespace 2.0

tonespace it's a different, more intuitive music keyboard, combined with a chorder.
tonespace it supports over 50 different grids, 14 scales, 18 keys, 30 chord types and 25 chord voicings.
tonespace it can function as a VST or Audio Unit plugin, processing incoming MIDI events and/or generating outgoing MIDI.

You don't need to use MIDI though: there is also a standalone executable which contains its own little synth for a fast start