CheeseCutter
An open-source SID editor that runs on modern machines but writes music for a real C64.
Unlike a tracker that lives on the C64 itself, CheeseCutter is a cross-platform desktop program (SDL) where the composer works against an emulated SID and exports a playroutine that runs on the metal. The interface is stripped down and keyboard-driven in the tracker tradition, built around hands-on control of the chip's three voices.
It shares its niche with GoatTracker and SID-Wizard but keeps its own following, especially among those who want tight control over arpeggios and table-driven effects. The output is a sidtune that plays in any SID player or drops into collections like the HVSC.