These are songs made with Milkytracker. Trackers allow you to open sound files as instruments or "samples" and arrange them on "tracks" in a system very familiar to me when I was coming from Pico-8. I typically use mostly samples from the ST-01 floppy disk that came with Soundtracker for the Commodore Amiga. Most of the songs I've made in Milkytracker belong to the original soundtrack of the game Nuclear RL, and as such go in a dedicated page for that game's OST.