A live tuning tool for Forza Horizon 6 on PC. Neptune connects to the running game and lets you change how your car behaves while you drive: torque delivery, boost and ride height.
| Tab | What it does |
|---|---|
| Engine | Reshape the torque curve by dragging it, set a torque multiplier and rev limit, hold anti-lag on a key to build boost off the line, and build extra boost while the game's own launch control holds you. |
| Turbo | Boost ceiling, extra torque, spool behaviour, synthetic lag, per-gear boost, a boost map you can shape per engine speed, and a scramble button for a burst of boost on demand. |
| Suspension | Set ride height per axle as a percentage, and drop the car on a key press with a smooth ramp. |
| Boost Gauge | A floating boost gauge on top of the game, as a dial, a digital readout or a bar. |
| Dragy | Time your car between two speeds, or over 60 ft, 1/8 mile and 1/4 mile, with an on-screen timer and recent runs. |
| Car | Shows which car you’re currently in, along with a preview of the car and how it’s aspirated.. |
| Tunes | Save your engine and turbo setup per car and switch between saved tunes with one key while driving. |
| Presets | Save and reload whole setups. |
| Settings | Units, display and startup behaviour. |
Anti-lag, launch control, air ride, scramble and tune switching can each be bound to a key, a controller button or a racing-wheel button, on their own tab. A control only ever drives one feature — binding one that is already in use takes it from whatever held it.
Every setting has a ? next to it. Hover or click it for an explanation of what that control does.
Grab the latest Neptune.exe from the
releases page.
Start the game and drive out into the world, then run Neptune. It needs to run as administrator to talk to the game, and will ask for that on launch.
Windows may warn about an unrecognised app, because the build is not
code-signed. Each release ships a SHA256SUMS.txt you can check against.
- Windows 10 or 11
- Forza Horizon 6 on PC (Steam or Microsoft Store)
- Python 3.11 or newer, if running from source
pip install -r requirements.txt
python -m neptune.app
Warning
Run your terminal as administrator, or Neptune will not be able to attach.
pip install pyinstaller
pyinstaller neptune.spec
The result is dist/Neptune.exe.
Tunes, presets and settings are written to a data folder next to the
executable, so you can move the whole folder to another machine and keep them.
If that location is not writable, Neptune falls back to %APPDATA%\Neptune.
The exact path is shown at the bottom of the Settings tab.
- Neptune reads and writes the game's memory only while you have it open. It makes no permanent changes to the game and installs nothing.
- Everything Neptune changes is put back when it closes. You can turn that off in Settings, and there is a Restore everything button at any time.
neptune/
core/ module contract, registry, runtime loop, settings, storage
memory/ process access, address table, pattern scanning
vehicle/ car discovery, identity and live state
ui/ theme, shell, reusable widgets
features/ one file per tab
utils/ some useful stuff
Adding a feature is one file in features/ and one line in app.py.
@DVS-code — Owner of this project and creator of its features.
@Zephyris-Pro — Collaborator with @DVS-code on implementing the memory module and designing the UI.
@HDR — Maintainer of the FH6 car ID list.
@D3FEKT — Owner of ForzaTechStudio. Special thanks for the implementation of .swatchbin support.
GNU General Public License v3.0. See LICENSE.
If you distribute a modified version, or a build of it, you must also make the source of your changes available under the same licence.
Neptune is an unofficial, fan-made tool. It is not affiliated with, endorsed by, or connected to Playground Games, Turn 10 Studios, Xbox Game Studios or Microsoft. Forza and Forza Horizon are trademarks of Microsoft Corporation.