Howdah

Howdah is a desktop app for playing and studying Arimaa. Play against engines on your own computer, analyse positions, keep annotated game records, and play or watch games on arimaa.com. It runs on Windows, Linux and macOS.

Features

Play and review

• The complete rules, including repetition and the one-minute setup allowance in timed games.
• Move pieces by dragging them along their route, with arrows on hover, or step by step with the mouse. Moves animate, and frozen pieces are marked.
• A move tree with variations, comments and move glyphs. Try a line anywhere in a game, and it's kept as a variation.
• Load and copy game records in the PGN-style Arimaa format, including games from the arimaa.com archive.
• Clocks and time controls, sounds, board and piece themes, and light and dark colors.

Engines

• Play against an engine, or watch two engines play each other.
• Sharp and OpFor can be installed from the Engines dialog with a click, and kept up to date there. Any other engine that speaks AEI can be added by its program path or a manifest.
• Set an engine's options for every game, for one game, or for analysis.

Analysis

• An engine searches the position on the board as you move through a game, showing its evaluation, its best line on the board, and its output. Click a line to add it to the game as a variation.

arimaa.com

• Log in to the gameroom to watch live games or open finished ones.
• Play: create and join games, rated or unrated, live or postal, with invitations, chat and takebacks.
• Games carry on through network drops and the computer sleeping, and you can return to a game in progress.

Install

Download the installer for your system from the latest release:

System	File
Windows 10 and 11 (x64)	Howdah_<version>_x64-setup.exe, or the .msi
macOS (Apple Silicon)	Howdah_<version>_aarch64.dmg
Linux (x86_64)	.deb (Debian, Ubuntu), .rpm (Fedora, RHEL), or .AppImage (any distribution)

The installers aren't code signed yet, so your system will warn you the first time you start Howdah:

• Windows: SmartScreen says it protected your PC. Click More info, then Run anyway.
• macOS: after macOS refuses to open it, open System Settings, go to Privacy & Security, and click Open Anyway next to Howdah. If macOS says the app is damaged, run xattr -dr com.apple.quarantine /Applications/Howdah.app in Terminal. (The macOS build is tested automatically but hasn't yet been tried by hand. Reports are welcome.)
• Linux: for the AppImage, make it executable first (chmod +x Howdah_*.AppImage) and then run it. It needs WebKitGTK 4.1 (libwebkit2gtk-4.1-0 on Debian and Ubuntu, webkit2gtk4.1 on Fedora), which most desktops already have. The .deb and .rpm install it for you.

The release's SHA256SUMS file lists each download's SHA-256 digest if you'd like to check it.

Howdah doesn't update itself. The releases page has new versions, and CHANGELOG.md what changed.

Troubleshooting

• Linux, blank window: on some NVIDIA or Wayland setups, start it with WEBKIT_DISABLE_DMABUF_RENDERER=1 howdah (or put the variable in front of the AppImage).
• Linux, no sound: sound goes through GStreamer; install gstreamer1.0-plugins-good (Debian, Ubuntu) or gstreamer1-plugins-good (Fedora).

Getting started

• Play an engine: open Engines and install Sharp or OpFor, then start a New game with the engine on one side.
• Analyse: turn on Analysis and pick an engine. It follows the position as you step through the game.
• arimaa.com: click arimaa.com and log in with your gameroom account to play, watch, or start games.
• Records: Record loads a game pasted in or opened from a file, and gives the current game's record to copy.
• Press ? for the keyboard shortcuts.

Building from source

Howdah is written in Rust with Tauri 2 and a Svelte and TypeScript frontend.

Prerequisites

• Rust (stable, 1.90+) and Node.js 22.12+ (or 24+) with npm.
• The platform packages Tauri needs:

Linux

Debian/Ubuntu:

sudo apt install libwebkit2gtk-4.1-dev build-essential curl wget file libxdo-dev libssl-dev libayatana-appindicator3-dev librsvg2-dev

Fedora: sudo dnf install webkit2gtk4.1-devel openssl-devel libappindicator-gtk3-devel librsvg2-devel libxdo-devel plus sudo dnf group install c-development.

The app itself only strictly needs libwebkit2gtk-4.1-dev and a C toolchain; the rest are for bundling.

Windows: Microsoft C++ Build Tools ("Desktop development with C++") and WebView2, which ships with Windows 10/11.

macOS: Xcode Command Line Tools (xcode-select --install).

Build and run

cd app
npm install
npm run tauri dev      # run the app with hot reload
npm run tauri build    # installers, in target/release/bundle/

Release installers also carry howdah-tourney, the engine test daemon:

npm run sidecar        # builds it into src-tauri/binaries/
npm run tauri build -- --config src-tauri/tauri.sidecar.conf.json

Test

cargo test --workspace                   # Rust: rules, engines, gameroom client, app logic
cargo clippy --workspace --all-targets
cd app
npm run check                            # svelte-check / TypeScript
npm test                                 # vitest
npm run e2e                              # Playwright smoke tests (needs Chromium)

CI runs these on Linux, Windows and macOS and builds the installers.

Layout

• crates/howdah-arimaa: rules, positions, notation, the game tree and game records. Pure Rust with no UI dependencies.
• crates/howdah-aei: an async AEI controller and engine-vs-engine matches.
• crates/howdah-gameroom: the arimaa.com gameroom client.
• crates/howdah-render: draws a position as a PNG or JPEG with the classic themes (cargo run -p howdah-render -- POSITION OUT.png).
• app/: the Tauri application. src-tauri/ is the Rust shell and src/ is the Svelte frontend.
• docs/: design notes (analysis, variations, engines, the gameroom, result codes, engine tests and tournaments).

Acknowledgements

The classic board and piece images come from the original arimaa.com client and have been released to the public domain. See app/src/themes/classic/ATTRIBUTION.md.

The sounds are made from samples in Kenney's audio packs (Interface Sounds, Casino Audio, Impact Sounds, Music Jingles, UI Audio and Digital Audio), released under CC0. Thanks, Kenney! See app/src/sounds/board/ATTRIBUTION.md and app/src/sounds/app/ATTRIBUTION.md for which samples went into which sound.

Finally, thanks to Omar Syed, not only for creating a great game but even more for his decades of effort keeping arimaa.com alive and working for players to enjoy.

License

MIT; see LICENSE.