掼蛋 (Guandan) is a four-player partnership card game from Huai’an, Jiangsu, hugely popular across the Yangtze delta. guan-dan brings it to the terminal — clean, fair, and open source, the way fight-the-landlord did for 斗地主.

Fair first

True random dealing — no card manipulation, no “new-player protection” tricks. Skill and luck, not algorithms and wallets.
Transparent rules — the engine and protocol are open source and auditable (MIT).
Server-authoritative — the pure engine crate validates every play; clients are thin.

What’s inside

Full core rules — level cards, wild cards (逢人配), the bomb ladder, tribute and anti-tribute, playing up through A.
Four players, two teams — classic partnership seating (0+2 vs 1+3).
Bot practice — one human plus three heuristic bots, no network needed beyond a local server.
Online rooms — create, join, or quick-match over WebSocket.
Keyboard and mouse — rank shortcuts, arrow selection, click to select, double-click to play, right-click to pass.
Bilingual UI — Chinese-first, with English where it matters.

Install

# macOS / Linux
curl -fsSL https://raw.githubusercontent.com/SihanTeng/guan-dan/main/install.sh | bash

# then
guandan                          # default ws://127.0.0.1:9100
guandan --server ws://host:9100

# Windows
irm https://raw.githubusercontent.com/SihanTeng/guan-dan/main/install.ps1 | iex

From source (Rust 1.75+):

cargo run -p guandan-server -- --bind 0.0.0.0:9100
cargo run -p guandan-client -- --server ws://127.0.0.1:9100

Controls (short list)

Input	Action
`←` `→` / click	Move hand cursor / select card
`Space`	Toggle card selection
Double-click / `Enter`	Play
Right-click / `P`	Pass
Rank keys `3`–`A`, `B`/`R`	Multi-select by rank
`C`	Card counter
`H`	Help
`Esc`	Back / clear

Under the hood

Rust throughout: guandan-core (pure rules), guandan-protocol, guandan-server, guandan-client, plus guandan-bot heuristics. Installers and CI live on GitHub Releases.