I tried that with "a dark snowday" and I personally think that one sounds the best out of the 4 of these world map tracks. It's currently the one with the most variance among the others, too.

The light world and dark world idea was just ripped from Super Meat Boy. The world menu themes are really short but really good!

Thanks for the generous vote, dude. Yeah, I agree with you about the harmony and chord stuff. If I wanted to make an actual song using this melody (which I kind of do), I would need to use chords and harmonies to prevent listening fatigue and add variation throughout it. That's an area I need to work on as most of my songs are simple loops!