For three years I have been looking for a Chapman Stick -- and finally now I have one!
The Chapman Stick resembles an electric guitar, but it is played with both hands in parallel by tapping or fretting the strings, rather than plucking them. Due to the two-handed approach, playing the Stick is as much related to playing keyboards as it is related to other stringed instruments.
The tuning is peculiar. The strings are grouped in a melody segment (to the left seen from the user) and a bass segment (the centre string and to the right). The melody strings are tuned in 4ths while the bass strings are tuned in reversed 5ths. While this surely prevents me from never learning how to find the scales, it nevertheless helps to produce exciting combinations.
Mastering such an odd instrument is not an easy task. I would be happy with only skimming the surface. For me, fast melodies and well structured chords seems hard to achieve, whereas jazzy rhythms and brave (dis)harmonies come more naturally.