A2 Racer II: reverse engineering and port

<img src="docs/media/cover.jpg" align="right" width="200" alt="The original Dutch box cover of A2 Racer II">

A study of the 1998 Windows racing game A2 Racer II (the Dutch release, v1.01), and a reimplementation in C that plays it on Linux and in the browser.

The research half is notes on how the original works, worked out from its binaries (mainly spel.dat, the renamed game executable) and from experiments with it running under Wine. Each finding records the code addresses it rests on and how sure it is.

The port is a new engine in C (SDL2, OpenGL) that reads the original game data unchanged. It runs the whole game: the intro video, the menu, the races, the results and the ending. The same sources build for the web with Emscripten.

<p> <img src="docs/media/amsterdam.jpg" width="32%" alt="Leaving Amsterdam at dusk, office blocks ahead"> <img src="docs/media/tunnel.jpg" width="32%" alt="Through a motorway tunnel at 179 km/h"> <img src="docs/media/plane.jpg" width="32%" alt="A KLM jumbo crossing the motorway"> </p>

All of these are the port, captured on the first stage, Amsterdam - Den Haag.

The game itself is not included. You need your own copy of A2 Racer II. Nothing here changes or redistributes the original files. The research is done on the Redump disc image A2 Racer II (Netherlands) (v1.01), which the Internet Archive keeps at archive.org/details/Redump.org14618.

Playing

You need CMake, a C compiler, SDL2 and OpenGL. Point the launcher at the game's data directory (the installed game, or the data folder of the CD or the extracted disc image: the one with spel.dat and RCS.IMG):

port/play.sh <game data dir>                # 1280x960 window
port/play.sh <game data dir> --fullscreen
port/play.sh <game data dir> --fresh        # forget the saved careers

It builds the port the first time. Your game directory is never written to: the game plays from a copy in ~/.local/share/a2racer2 (or $A2_PLAY_DIR), which also keeps your careers between runs.

In the browser

port/web/build.sh    # needs Emscripten (emcc)
port/web/serve.sh    # then open http://localhost:8080/a2racer2.html

The page asks for your A2 Racer II folder once and keeps the files it needs in the browser's storage.

Layout

Path	Contents
research/discoveries.md	What has been established, with evidence
research/hypotheses.md	Ideas that are not settled yet
research/open-questions.md	Open and resolved questions
reverse-engineering/	Reference docs: executables, file formats, game and menu architecture, running the original under Wine
reverse-engineering/tools/	Disassembly helpers, Unicorn emulation harnesses and gdb scripts used to check findings
reverse-engineering/analysis/	Function lists, source-file map and annotations taken from the binaries
port/	The C port; port/README.md is its detailed manual
port/web/	The WebAssembly build
port/a2tools/	Python tools for the game's archives, images, sprites and car data

How the research works

Each finding carries a label: CONFIRMED, STRONGLY SUPPORTED, LIKELY or SPECULATIVE. The notes never present an inference as fact. Evidence from the binaries and from runtime experiments comes before outside documentation. Where the port's behaviour comes from the original, its source comments name the address it was taken from, for example 0x4190d0 for the sky. Where the port deliberately differs, port/README.md says so. The working rules are in AGENTS.md.

The original runs under Wine without the CD (it honours a NOCD environment variable), which makes side-by-side comparisons possible; see reverse-engineering/runtime-wine.md.

Some tools in reverse-engineering/tools/ need Python 3 with capstone, pefile and unicorn, and some run inside gdb.

Status

The full game is playable from start to finish. The remaining differences from the original are listed under "Known gaps" in port/README.md, and the unanswered questions are in research/open-questions.md.

License

This software is released under the BOLA License. It covers this project's own code and notes, not the game.

Legal

A2 Racer II, its data and its box art (Davilex, 1998; the cover image is from IGDB) are the property of their rights holders. This project contains no game data and is meant for people who own the game.