Vₑ — a clean-room Escape Velocity engine

Vₑ ("vee-sub-e" — the physics symbol for escape velocity, and EV backwards) is a from-scratch reimplementation of Ambrosia Software's classic Escape Velocity (Mac, 1996). It runs in the browser, and ships no game content — you play it with your own copy of the original.

Play it

The easiest way needs no command line and no tools. Serve the repo over http (a service worker needs a secure context; localhost counts) and open the loader:

python3 -m http.server        # from the repo root
# → http://localhost:8000/loader/

Drop your original Escape Velocity … .sit onto the page. Everything — StuffIt unpacking, resource decoding, QuickDraw graphics, sound, and building the engine — happens in your browser. Nothing is uploaded; your data never leaves the device. See loader/README.md for how the in-browser pipeline works.

Prefer the command line? make builds flight.html from a local copy of the data (see Building).

What works

It's a real game, not a tech demo. From a fresh pilot in Levo you can:

• Fly and fight — 60 Hz inertial flight from the ship's own stats, warship and trader AI, the bible-exact damage model, projectiles/beams/ammo, escape pods and disintegration.
• Explore — a galaxy map with fog of war, hyperjump with fuel, and landing on planets with their real landscape art and description text.
• Trade and outfit — the six-commodity exchange, plus a tech-gated outfitter and shipyard in the original grid-and-detail layout.
• Take missions — cargo runs, destroy/disable/board/escort/rescue jobs, and branching storylines, offered at the spaceport bar and mission computer; a legal record and combat rating gate what you're offered and draw bounty hunters when you turn criminal.
• Board, capture, and command — loot or capture disabled ships, keep captures (or hired escorts) as a fleet, get work from named characters, and carry fighters in bays.

Rounding it out: the original title screen and music, positional audio, pilot saves, and touch controls for phones and tablets.

How it's built

The game's declarative data lives in Classic Mac resource forks; a small zero-dependency toolchain lifts it into plain JSON that the engine consumes:

• evrsrc.js — reads resource forks (MacBinary / AppleDouble / raw).
• schemas/*.json — record layouts, generated from the TMPL resources inside EV's own data file by tmpl2schema.js (authoritative, not guessed).
• semantics.js — meaning for the raw fields (flag bits, enums, ID conventions), sourced from the EV Resource Bible. Facts, not expression.
• evexport.js — assembles the game database and builds galaxy.html / flight.html; evconvert.sh + evsprites.sh turn PICT/snd resources into PNG/WAV sprite sheets.

The flight rules live once, normatively, in engine/ENGINE_SPEC.md, implemented by the DOM-free engine/core.js. The browser UI around it — canvas rendering, dialogs, input, game state — is the shell: real ES modules under engine/shell/*.js, split by domain, with main.js as the entry point. esbuild bundles core.js into engine/core.bundle.js and the shell into engine/shell.bundle.js; the build injects both bundles, with the game data, into flight_template.html. (The bundles are generated and gitignored; a release ships them, and the browser loader builds them on demand.)

The browser loader in loader/ is a second, dependency-free implementation of that whole pipeline (StuffIt decompression, PICT/snd /sprite decoders, the database builder) so the game can be assembled client-side from a dropped .sit. node loader/verify.js checks its decoders against the native tools' output byte-for-byte.

Building from source

You need a local copy of the game's data in EV_data/ (never committed — see Legal). A top-level Makefile wraps the common tasks:

make            # build flight.html (the browser game)
make galaxy     # build the galaxy map viewer
make verify     # check the loader's decoders against the native tools
make help       # list all targets

The build is driven by placeholder injection: esbuild bundles engine/core.js and the engine/shell/*.js modules (entry main.js) into engine/core.bundle.js and engine/shell.bundle.js, then evexport.js slots those two bundles, the game database, and the sprite manifest into flight_template.html. Dev/test hooks are URL params on flight.html — e.g. ?syst=, ?ship=, ?x=&y=&heading=, ?map=1, ?land=1 — handy for jumping straight into a scenario.

Legal

The engine is clean-room and yours to use. The scenario — art, text, sounds, and the universe itself — is still Ambrosia's copyrighted work. Vₑ ships none of it: EV_data/, evdata.json, evassets/, galaxy.html, and flight.html are gitignored build inputs/outputs and must never be committed or hosted. This is the same posture NovaJS and Kestrel take. The browser loader is designed around it — your data is decoded on your device and never touches a server. (This isn't legal advice; "abandonware" has no legal standing, and Ambrosia's closure didn't release the rights.)

References

Field-by-field record docs live in the community-archived EV/Nova Bibles and the EVNEW source (mirrored at escape-velocity.games/docs); ResForge is a maintained editor with TMPL definitions. The project roadmap and status are in PLAN.md.