leeneia -

A fretted dulcimer has the same notes as a harmonica, and lots of people play blues on harmonicas. The trick is to get into the right mode, and "fake" the few "accidentals" that aren't there by playing a substitute note that's "in the chord." If you can find a good harmonica site, look for "cross-harp" techniques.

Although it's a bit clumsy for practical use, you can also play notes that are in between the frets if you're using a noter. If you place the noter on the string between frets without pressing the string down agains the nearby frets, and also press the end of the noter against the fingerboard, you can make it sound notes that aren't fretted. This is more of a parlor trick than real music, but it might impress someone sufficiently gullible. To do it if you're fingering without a noter, you could theoretically, perhaps, get the effect with v.e.r.r.r.y. l.o.o.o.o.n.g fingernails.

(Most of the sound on a fretted dulcimer gets to the dulcimer top (soundboard) by going through the fret, so you need the noter (or long fingernail) to conduct the sound into the fingerboard if the string isn't against a fret.)

With practice, you can "sort of" play chromatic scales on a dulcie.

John