ctrlassist-0.2.0 is not a library.

CtrlAssist brings "controller assist" functionality to Linux gaming by allowing multiple physical controllers to operate as a single virtual input device. This enables collaborative play and customizable gamepad setups, making it easier for players of all ages and abilities to enjoy games together. While similar features exist on modern game consoles, CtrlAssist is an open source project that enhances accessibility for PC gaming, offering additional quality-of-life improvements through virtual input devices on Linux.

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Features

Combine physical controllers into one virtual gamepad
- Controllers are assigned as either Primary or Assist
Customizable multiplexing modes for buttons and axes
- Logically merging or preempting events is flexible
Hide physical controllers for improved game compatibility
- Avoid controller interference from conflicting inputs
Spoof gamepad vendor for in-game layout recognition
- Mimic either Primary or Assist controller hardware
Rumble pass-through from virtual to physical devices
- Forward force feedback to either or both controllers

Modes

Priority (default): Assist controller overrides when active
- Axes: Prioritize Assist when active (exceeds deadzone)
  - Buttons: Prioritize Assist when button released
  - Triggers: Prioritize largest value from either
- Ideal for partial and asynchronous assistance
  - E.g. Assist for movement while Primary for actions
Average: Blend weighted inputs from both controllers
- Axes: Averaged when both are active (exceed deadzone)
  - Buttons: logically OR'ed between pressed controllers
  - Triggers: Averaged when both are active (exceed deadzone)
- Ideal for cooperative input and subtle corrections
  - E.g. For counter steer/brake assist in racing games
Toggle: Switch Active controller on demand
- All inputs forwarded from currently active controller
  - Toggle Active controller via the Mode button on Assist
  - Immediately synchronizes input to current Active state
- Ideal when fine-grain conflict-free control is needed
  - E.g. Game menu navigation or precise interventions

Prerequisites

Linux system using udev (libudev-dev)
- with user permissions to manage virtual devices
- already pre-configured on most distributions
Rust toolchain with included cargo
- https://rust-lang.org/tools/install/
- configure PATH per Notes linked above

Install

Add the --force flag to upgrade to latest version:

cargo install ctrlassist

Usage

Use the --help flag for information on each CLI subcommand:

$ ctrlassist --help
Multiplex multiple controllers into virtual gamepad

Usage: ctrlassist <COMMAND>

Commands:
  list  List all detected controllers and respective IDs
  mux   Multiplex connected controllers into virtual gamepad
  help  Print this message or the help of the given subcommand(s)

Options:
  -h, --help     Print help
  -V, --version  Print version

list

List all detected controllers and respective IDs:

$ ctrlassist list
(0) Microsoft Xbox One
(1) PS4 Controller

mux

Multiplex first two detected controllers by default:

$ ctrlassist mux
Primary: (0) Microsoft Xbox One
Assist:  (1) PS4 Controller
...
Mux Active. Press Ctrl+C to exit.

Optional: Specify Device Mapping

Manually specify Primary and Assist controllers via IDs:

$ ctrlassist mux --primary 1 --assist 0
Primary: (1) PS4 Controller
Assist:  (0) Microsoft Xbox One
...

Optional: Specify Mux Mode

Manually specify mode for merging controllers:

$ ctrlassist mux --mode priority
...

Optional: Hide Physical Devices

Avoiding in game conflicts by hiding physical controllers:

$ sudo ctrlassist mux --hide
...

Optional: Spoof Virtual Device

Mimic controller hardware for in-game layout recognition:

$ ctrlassist mux --spoof primary
Primary: (0) Microsoft Xbox One
Assist:  (1) PS4 Controller
Virtual: (2) Microsoft X-Box One pad (Firmware 2015)

Optional: Proxy Rumble Effects

Target force feedback to either or both physical controllers:

$ ctrlassist mux --rumble both
...

Limitations

Hiding physical input devices requires root access
- temporarily modifies group permissions for selected devices
Hiding must be done before starting games or launchers
- processes with open file handles may retain device access
Reconnecting a hidden controller reverts its visibility
- custom udev rules should be used for persistent permissions
Toggle mode requires pressing all buttons and axes after startup
- gilrs lazily initializes gamepad state used for synchronization

ctrlassist 0.2.0