(update: fixed audio quality)
I used Sunsoft's classic NES DPCM Bass samples, as well as bit-reversed DPCM percussion samples from Gimmick!, made by YoshiLightStar: https://www.youtube.com/watch?v=VsVkIbpFMhs Original composers are Masanori Hikichi and Masayuki Nagao. I used Bitwig Studio 4.2 to create this. I loosely based my style off of the NES soundchip, but didn't restrict myself to the limited voices that the NES uses. Image is by me, but it's an edited screenshot I took using the Sega Master System emulator MEKA.