VCThunder

Vibe Code Thunder is a Midway Quicksilver II Windows host for Hydro Thunder (1999) and Offroad Thunder (2000).

VCThunder is not an emulator. The original 32-bit x86 game code runs natively on your CPU, in-process, unmodified. What VCThunder replaces is everything around that code: the Phar Lap ETS kernel becomes real Win32, the Glide 2.53 boundary becomes our own rasteriser, and the cabinet's I/O boards, audio hardware, timebase and NVRAM become host implementations.

This project was a personal challenge to see how far Claude Opus 5 could be leveraged to fully vibe code an application like this, and succeeded far beyond expectations.

Building

Build from WSL or from an MSYS2 MINGW32 shell, not from PowerShell or cmd.

0. Get the toolchain. i686-w64-mingw32-gcc, make and python3.

sudo apt install gcc-mingw-w64-i686 make python3   # WSL / Debian / Ubuntu
pacman -S mingw-w64-i686-toolchain make python     # MSYS2, from the MINGW32 shell

1. Put your two game CHDs in chd/. You supply the legal dumps.

2. Unpack the games:

python3 tools/ingest-chd.py --auto

It finds the CHDs, works out which game each one is by looking inside it, unpacks both into data/, and checks each for correctness.

3. Build and stage it:

make setup

It fetches SDL3, builds the address tables, builds the host, and writes a playable pack into run/vcthunder/.

4. Launch it:

run/vcthunder/VCThunder.exe

docs/building.md is the long build doc, including the layout the build expects and the smoke test.
docs/configuration.md covers every ini key and the controls the pack ships with.
docs/architecture.md explains how the host is put together.

Supported builds

Every address VCThunder patches is an offset into one exact executable. This host supports exactly two files:

Title	Build	SHA-256 of the executable
Hydro Thunder	v01.01b, 1999-02-27	a421f5fd4ee0d90f57815975d4a47bb784f2b46d48085e42b422605a029f8e3f
Offroad Thunder	2000-02-25	fa739d0f1a80c6e429ca73fdee04c3d6d6325bb95848cb701114f74bf2a5e9bf

tools/ingest-chd.py hashes what it extracts and says which you have.

State

V0.2, the second public beta release.

Both titles playable: gameplay, controls, audio, NVRAM, windowing, force feedback, and I/O, at a locked 30 fps.

Title	Released	I/O board	State
Hydro Thunder	1999	Diego	Playable
Offroad Thunder	2000	MagicBus	Playable

Link play is an early beta: only two instances on one machine have ever been linked. That's it.

Roadmap

The goal is a replacement system for the original Quicksilver II cabinets.

Todo:

• Link play between two machines: both simulated and real cabinet.
• Real cabinet IO: the Diego and MagicBus I/O boards over RS232, and the security relay a real board originates.
• Real cabinet video: native 25 kHz to the cabinet's own monitor, at the game's own 512x384 coin-op timing.
• Linux support and Vulkan renderer.
• Bugfixes and comparison to real hardware where possible.

Licensing

Original VCThunder source and documentation are MIT-licensed. See LICENSE.

The renderer's GPU backend uses SDL3, under the zlib license and © the SDL contributors. make deps downloads the official pinned release and verifies its SHA-256, and make pack copies SDL3.dll beside the host binaries.

Hydro Thunder, Offroad Thunder, Midway and 3dfx marks belong to their respective owners. This project is unaffiliated with them and exists for preservation and for interoperability with hardware its users own.