SkyRoads — a 1:1 reverse-engineered portable port

In 1993, Bluemoon Interactive — the Estonian studio whose founders later built the technology behind Kazaa and Skype — released SkyRoads, a gorgeous space-racing game for DOS. The source code was never published.

This repo is a from-scratch reverse engineering of that game: the original SKYROADS.EXE was disassembled, every file format and algorithm was recovered from the machine code, and the whole engine was rewritten as ~3,000 lines of portable C11. It runs today on macOS, Windows, Linux, the web (Emscripten), and iOS — with the exact 36.0036 Hz timing, fixed-point physics, and pre-baked-perspective renderer of the original.

Made as a love letter to Bluemoon Interactive and everyone who spent the 90s bunny-hopping down neon roads in space. All game content is theirs; SkyRoads was released as freeware.

How faithful is it?

This is not a remake "in the spirit of" the original — it aims to be the same game:

• No original code executes. The engine is new C, linking only SDL2.
• Demo-proven physics. The original's 1993 attract-demo input recording (DEMO.REC) is position-indexed raw input. Replayed through this engine's reimplemented physics, it completes the entire demo road tick-for-tick — jump arcs, boost pads, sticky tiles, collisions, and the hidden landing autopilot all have to be exact for that to work. It's a regression test: ctest --test-dir build.
• Receipts included. docs/FORMATS.md specifies every file format, and re/notes/ documents the recovered game logic with the EXE instruction address for every constant.
• Original data, untouched. The engine reads the unmodified retail files at runtime. No converted assets.

Getting the game data

This repository contains no Bluemoon files. SkyRoads is freeware — download it from bluemoon.ee and copy the data files (*.LZS, *.DAT, *.SND, DEMO.REC) into the repo root (they're gitignored), or pass their folder to the executable.

Build & run

cmake -B build -S . && cmake --build build
./build/skyroads /path/to/skyroads-data     # or run from the data dir

Web, iOS (including TestFlight), and Windows cross-builds: see docs/PORTING.md.

Controls: arrows steer/throttle, Space jumps, Esc back, P pause — same as DOS. Touch (iOS): d-pad lower-left, jump button lower-right.

Make your own tracks

Because the formats are fully decoded, the game is moddable:

python3 tools/make_track.py /path/to/gamedir /tmp/mod

builds a brand-new road (custom layout, palette, gravity/fuel/oxygen) and splices it into a copy of ROADS.LZS. Tile semantics are in docs/FORMATS.md §3 — geometry, tunnels, boost/sticky/ice/burning surfaces, fuel pickups, per-road palettes are all yours to edit.

Layout

• src/core/ — platform-independent engine core (C11, no OS calls)
• src/platform/ — SDL2 shell (desktop/web/iOS), iOS bundle bits
• src/tools/ — headless render/demo/music test harnesses
• tools/ — Python: format extractor, LZS codec, track builder
• docs/ — format specs and porting guide
• re/ — function map and per-subsystem reverse-engineering notes

Credits

• Bluemoon Interactive — SkyRoads (1993): game design, art, music, and three decades of inspiration. Copyright remains theirs.
• Port by Ammaar Reshi and Claude (Fable 5), reverse engineered from the retail binary in roughly a day.
• Nuked-OPL3 (LGPL-2.1) for Yamaha OPL2 chip emulation; font8x8 (public domain) for two strings of UI text.

License

The port's source code is MIT (see LICENSE), except src/thirdparty/ which keeps its upstream licenses. SkyRoads game content is not covered by this license and is not distributed here.