Slipstream: A Rocket League Launcher

Slipstream is a standalone, cross-platform app that launches the Epic Games version of Rocket League without the Epic Games Launcher.

This project builds upon the original RocketLeagueLauncher by HiDefCode.

Key Benefits

• Integrate with Steam: Add the Epic Games version of Rocket League to Steam. This enables full support for the Steam Overlay, controller configurations, and the Steam Deck.
• Launch Options: Easily apply launch options to skip movies, launch without Easy Anti-Cheat, or open in RLBot mode.
• Skip the Epic Launcher: Play Rocket League without the Epic Launcher running in the background. Perfect for standalone use or with other launchers like Playnite and Lutris.
• Simple Multi-Account: Easily switch between Epic accounts in Rocket League using custom config files.
• No Dependencies: A single, dependency-free executable.

Installation & Setup

Prerequisite: Rocket League must be installed and kept up-to-date via a game manager (e.g., Epic Games Launcher, Heroic Games Launcher). Slipstream only launches the game.

1. Download & Prepare

1. Go to the Releases page and download the executable for your platform.
2. Place the downloaded file in a new, dedicated folder. Slipstream will store its configuration file (config.json) here.

2. First-Time Setup (Windows)

Note: If you play with a controller (Xbox, PlayStation, Steam Controller), follow these steps exactly so your inputs work correctly through Steam.

1. In Steam, select Add a Game -> Add a Non-Steam Game..., browse for Slipstream.exe, and click Add Selected Programs.
2. Launch Slipstream directly from your Steam library.
3. The app will prompt you to select RocketLeague.exe.
4. Your browser will open to the Epic Games login page. Log in, copy the 32-character authorizationCode from the final page, and paste it into Slipstream's dialog.
5. The game will launch, and your settings will be saved.

Note for Keyboard & Mouse Users: If you don't need Steam's controller support or overlay, you can skip adding it to Steam and just double-click the .exe directly.

2. First-Time Setup (Linux / Steam Deck)

1. Add the downloaded Slipstream.exe to Steam as a non-Steam game (Steam Deck users must do this in Desktop Mode).
2. Right-click the game in your Steam library, go to Properties -> Compatibility, and force the use of the latest Proton version.
3. Launch the game through Steam. The app will prompt you to select RocketLeague.exe.
4. Your browser will open to the Epic Games login page. Log in, copy the 32-character authorizationCode from the final page, and paste it into Slipstream's dialog.
5. The game will launch, and your settings will be saved.
6. Once the game launches successfully, you can return to Gaming Mode. Slipstream will continue to boot directly from your Steam library with full controller support. (Note: If this method fails, you can use the native Linux binary (chmod +x Slipstream && ./Slipstream) to run the initial setup first).

Usage

• Updating Slipstream: Slipstream will automatically notify you about new versions. To update, simply replace your executable with the latest one from the Releases page. Your config.json is preserved.
• Custom Launch Options:
  1. In Steam, right-click Slipstream -> Properties...
  2. Under General, enter options in Launch Options (e.g., -nomovie -high). These are passed to Rocket League.
  • To launch without Easy Anti-Cheat (EAC): Add -noeac to your launch options. Slipstream will intercept this and launch the base game executable instead, allowing for offline play and modding.
  • To play with RLBot: Add -rlbot along with your bot parameters (e.g., -rlbot RLBot_ControllerURL=127.0.0.1:23233 RLBot_PacketSendRate=240) to your launch options. Slipstream will automatically ensure the -rlbot flag is passed first, as required by the bot API.
• Multiple Accounts:
  1. Add the Slipstream executable as a game to Steam (or another launcher) a second time.
  2. In the launch options (Steam Properties -> General -> Launch Options), append the --config= argument with your desired filename (e.g., --config=smurf.json).
  3. Run the shortcut to perform first-time setup for this new configuration.
  4. You can create as many configurations as you need without copying the executable.

FAQ & Troubleshooting

Q: My Steam Deck controls / Steam Controller / PlayStation controller doesn't work!

You are likely launching Slipstream directly from your desktop. To use Steam Input (which is required for these controllers and custom deadzones), you must add Slipstream to Steam and launch it directly from your Steam library.

Q: Will Slipstream update Rocket League automatically? / "Version Mismatch" error

Since Slipstream bypasses the Epic Games Launcher, it also bypasses Epic's automatic game updates. If you receive a "version mismatch" error when trying to play online, open the Epic Games Launcher (or Heroic) to let the game patch, then close it and use Slipstream again.

Q: How does Slipstream handle Easy Anti-Cheat (EAC)?

Slipstream automatically detects your game path and launches the RocketLeague_EAC.exe version by default, ensuring online play works out-of-the-box. Existing users do not need to update their config.json; Slipstream intercepts the launch and corrects the path in memory. If you wish to play offline without EAC, add -noeac to your launch options.

Q: Do I still need the Epic Games Launcher installed?

Yes (or an alternative like Heroic), for installing and updating Rocket League. Slipstream lets you play without running the Epic Launcher.

Q: Does this improve in-game FPS?

It can speed up game boot time but shouldn't affect in-game FPS.

Q: What's the difference between this and Heroic/Legendary?

Slipstream is minimal, focused only on launching Rocket League via other launchers (like Steam) without extra dependencies. Heroic/Legendary manage entire game libraries.

Q: Does Slipstream modify game files?

No. It only reads your game path to launch the game.

Q: My game is in the wrong language, how do I change it?

The Epic Launcher normally passes a language argument to the game. You can do this yourself in Slipstream's launch options. To force English, add -language=INT. Other common codes include DEU (German), FRA (French), and ESN (Spanish).

Building from Source

Requires Go toolchain (v1.24+).

1. Clone: git clone https://github.com/jun-eau/Slipstream.git
2. Navigate: cd Slipstream
3. Build:
   • Windows (64-bit): go build -o Slipstream.exe .
     • Cross-compile on Linux/macOS: GOOS=windows GOARCH=amd64 go build -o Slipstream.exe .
   • Linux (64-bit): go build -o Slipstream .
     • Cross-compile on Windows: $env:GOOS = "linux"; $env:GOARCH = "amd64"; go build -o Slipstream .

The executable will be in the project directory.

Deprecated Features

Legacy Feature: BakkesMod Setup (Deprecated)

DEPRECATION WARNING: BakkesMod is no longer in active development and is blocked by Easy Anti-Cheat. Slipstream now treats BakkesMod as a "Legacy Offline" feature. If BakkesMod is enabled in config.json, Slipstream will automatically force the game to launch without EAC (effectively applying the -noeac flag automatically), restricting you to offline modes only. To play online, you must disable BakkesMod in your configuration.

Slipstream can automatically launch BakkesMod. If enabled during initial setup, you'll be prompted for BakkesMod.exe.

Windows:

1. Install BakkesMod from bakkesmod.com.
2. When Slipstream asks, locate BakkesMod.exe (usually C:\Program Files\BakkesMod\BakkesMod.exe).

Linux (using Wine/Proton): BakkesMod is a Windows application, so it runs within Wine/Proton.

1. Download BakkesModSetup.exe from bakkesmod.com.
2. Install it using your Wine/Proton environment:
   • Proton (via Steam): Add BakkesModSetup.exe as a non-Steam game, force the same Proton version as Slipstream/Rocket League, and run it once.
   • Wine (standalone): wine /path/to/BakkesModSetup.exe.
3. Point Slipstream to the installed BakkesMod.exe within your Wine/Proton prefix (e.g., ~/.wine/drive_c/Program Files/BakkesMod/BakkesMod.exe or ~/.steam/steam/steamapps/compatdata/<AppID>/pfx/drive_c/Program Files/BakkesMod/BakkesMod.exe).

If "Mod is out of date, waiting for an update" appears: In the BakkesMod window (once running with Rocket League), go to "Settings", uncheck "Enable safe mode", and click "Yes" on the warning.

Steam Deck Users: Navigating the BakkesMod window in Gaming Mode may require using the Steam button to access window controls.

For detailed Linux help, see the BakkesLinux guide (Setup/Installation sections). Additionally, for a step-by-step walkthrough of using Slipstream with Heroic (including auto-updates), see the bakkeslinux guide by @beidoubagel.

License and Credits

This project is open source (see LICENSE file).

It's a derivative of RocketLeagueLauncher; special thanks to HiDefCode for releasing the original work under The Unlicense.