Lefty

Remap any key for left-handed gaming. Low latency, native Rust engine.

What is it?

• WASD → IJKL (or arrows, numpad) for left-hand movement
• Map any key to any other: I→W, Q→U, Caps→Ctrl, Win→Disabled — or combos like I→Ctrl+S
• Mouse side buttons as sources: MOUSE_X1→R, capturable with a click
• Profiles you can create, rename, duplicate, reorder and delete (Lucide icons, tabbed editor)
• Games list per profile: auto-switches and works only in your games (empty = manual)
• Game recommendations: browse installed Steam/Epic games with covers, or capture the app in focus
• Pause individual mappings without deleting them
• Add-mapping validation: duplicate sources and self-maps are blocked inline
• Live key tester: see what the game receives before saving
• Accent Color themes: 10 presets + custom picker, per-profile override, high-contrast mode (Settings → Appearance)
• Share profiles with compact codes (⋯ → Share), review before importing, automatic backups
• Interface sounds: distinct chimes for activate vs pause (Settings → General)
• Gaming focus: Sticky/Filter key popups stay silent while active
• Tray menu: switch profiles and pause/resume without opening the window
• Launch options: autostart, start minimized, start active
• Update checker with in-app download + guided tour included
• Tabbed Settings: General, Appearance, Input, Profiles, About
• Works in any game (low-level hook)
• Very low latency native Rust engine (verify live in Settings → About)
• Clean dark UI

Screenshots

Main window

Mappings

Add mapping	Delete mapping

Settings

General	Appearance

Input	Profiles

Install

Download the latest installer from Releases (Lefty_*_x64-setup.exe).

Run as Administrator for games that run elevated.

Profiles

Profile	Mapping
Left-handed IJKL	I→W, J→A, K→S, L→D + mirrored cluster
Arrow Keys	↑→W, ←→A, ↓→S, →→D + cluster
Numpad 8456	8→W, 4→A, 5→S, 6→D + digits
OKL; Mirror	O→W, K→A, L→S, ;→D + mirror

Create your own with + (rename, icon, accent and games from tabs, reorder from ⋯).

Usage

1. Pick a profile on the left
2. Add or Capture a mapping (I → W)
3. Activate
4. Play (activate before launching the game)
5. Pause to restore, F6 to toggle, close to tray
6. Share via ⋯ → Share on any profile, import by pasting the code in Settings → Profiles

Latency

Method	Latency
Registry	0ms (reboot, not dynamic)
Lefty	low latency*
AutoHotkey	5-15ms

*Verify it yourself live in the app: Settings → About → Engine latency.

Structure

Lefty/
├── engine_native/ # Rust engine (hook + SendInput + telemetry)
├── tauri-app/     # Tauri v2 + React UI
├── assets/        # banner + screenshots
└── dist/          # local test binaries (gitignored, see Releases)

Troubleshooting

• Not working in game: Run as Admin. Some anti-cheats block hooks → use Interception.
• Stuck key: Pause and resume.
• High delay: Close other hooks (AutoHotkey).

Community

Questions, layouts to share, bug reports:

Acknowledgments

• Remapping architecture inspired by Microsoft PowerToys Keyboard Manager (low-level hook + SendInput design, Task Scheduler autostart pattern) — reimplemented from scratch in Rust with a zero-GC hot path, batched injection and live latency telemetry for lower, measurable latency.

License

MIT — Made for left-handed gamers.