A Field Guide to Tracker Formats

People say "chiptune" like it means one thing. It does not. Here is the lay of the land, roughly chronological.

The Amiga lineage

MOD (ProTracker) — 4 channels, samples baked in. The format. If you only learn one, learn this. Patterns of notes, a sample bank, done.
Future Composer (1.0–1.4) — synth-driven rather than sample-heavy; tiny files because the instruments are generated, not stored.
Jochen Hippel (regular + COSO) — Hippel's own engine; COSO is the compressed variant. Distinctive, dense, unmistakable.
David Whittaker, SoundMon, Delta Music, Digital Mugician — a whole zoo of composer-specific engines, each with its own quirks.

SID (C64) — not samples at all but a register dump driving the MOS 6581 chip. Three voices, analogue filters, pure magic. Playback means emulating the chip.
XM (FastTracker II, PC) — the Amiga model with more channels, more effects, and instrument envelopes.

This framework plays all of the above. Point introTrack (or any <audio>-ish hook) at a file and the engine routes by extension:

.mod .xm .s3m .it   ->  libopenmpt
.fc .fc14 .hip      ->  Flod (Amiga chip)
.sid                ->  jsSID
.mp3 .ogg .wav      ->  native

One toggle, any format. The scene's entire back catalogue, in a browser tab.