STARS — JavaScript port of Noooon's 1995 MS-DOS demo

A reverse-engineered reimplementation of STARS: Wonders of the world (STARSv2.EXE, Noooon, 1995) in plain JavaScript: all effects redrawn in a 320×200 indexed-colour canvas, original music played through libopenmpt.

• Play: https://kassoulet.github.io/stars_by_nooon/ (landing page → demo)
• Write-up: web/writeup.html — how the EXE was unpacked and how each effect works.

Run locally

python3 -m http.server -d web      # then open http://localhost:8000/

Click once to start (audio needs a gesture). Keys: Space pause · ←/→ seek ±5 s · F fullscreen.

Layout

Path	Content
STARSv2.EXE	the original demo (target); STARS.EXE is an older version, ignored
web/	the site: index.html (landing), demo.html + main.js (runner), script.js (timeline), engine.js, lib3d.js, parts/*.js (one module per effect), assets/ (decompressed resources), stars.xm (music), timeline.json
re/	reverse-engineering: NOTES.md (process), emu_unpack.py, dlz.py, extract.py, images.py, mod2xm.py, ref/harness.py (Unicorn harness running the original code as ground truth), parts/*.md (per-effect notes)

Method (short)

Self-decrypting stub (emulated with Unicorn) → PKLITE-style LZ → flat 32-bit image (PMODE 3.07) → resource container with a custom dlz compressor. Each effect was disassembled, ported to JS and compared pixel by pixel with frames produced by the original code in the harness. See re/NOTES.md.

Known gaps

• Part I's second half is not verified against the original; text-mode ending screen not ported.
• Parts assume one tick per frame (70 Hz); the original's animation speed may differ on slow frames.
• Random dots in the text part can't match the original exactly (seed depends on earlier parts).
• Seeking replays effects from the start of the current part, so a seeked frame can differ slightly from a normal run.
• Music is converted MOD → XM and played by libopenmpt, so mixing differs from the original LCA player.

Credits

Original demo by Noooon (Groo: music, Bartie: 3D motion, Karl: system and effects, Ra: script and pixels), 1995. Sound: LCA player by Cedric Bermond; protected mode: PMODE by Tran. Playback: libopenmpt via chiptune3. This port was produced by reverse engineering with AI assistance (Claude).