When composing instrumental music for film or radio I often use melodic harmonies. Instead of accompanying a melody with chords, I use chords to play the melody. This way several layers of melodies can be heard at the same time which adds depth to the music. And as a listener you will discover the different melodic lines, layers which are played against each others.
Maybe you want to make a specific melody stand out of the harmony/chords a bit? You achieve this by adding velocity values to specific notes. It can easily be done by MIDI programming but is almost impossible to play on a regular keyboard.
Melodic harmonies don’t need to be restricted by one instrument playing all the chords but you can see the whole arrangement as one big orchestra playing harmonies with a strong melodic goal. The possibilities are endless when put the whole concept “chord are for accompanying a melody” on its head. Several instruments can “help” each other by playing melodic sounding harmony lines.
Melodic harmonies is not a new thing by the way, much classical music is arranged this way. As well as big band music and some modern electronic music.
I have a jazz background so adding more notes to the harmony is what I like. Complex chords, stuff like additional 6’s, 9’s, 11’s, flat or sharp. But even when you keep it simple, for example using the simple minor and major triads, you can make very interesting harmonic structures by adding lines containing 2 notes at the same time instead of just 1.