Custom Snow Theme: New Super Mario Bros. Soundfont Music
I know nothing about music theory. Evidently, I have forgotten the time of year as well.
Made with Waveform Free, Sforzando, and Audacity using a mix of NSMB audio samples/MIDIs from the Internet and audio samples/MIDIs directly taken from the game's ROM. Gameplay from OpenEmu v2.3.3.