♟️ Real-Time Multiplayer Chess — Phoenix LiveView

A two-player online chess game where both boards update live over a single shared link — no page reloads, no polling. Built in a 24-hour individual hackathon at the Doofinder Code Challenge 2022, where it won the Knight Award (most original project).

🏆 Knight Award — Most Original Project, Doofinder Code Challenge (Oct 2022)

What it does

• Real-time multiplayer chess for two players over the web.
• Create a game at a shareable URL — send the link, your opponent joins, you're playing.
• Moves render on both boards instantly via Phoenix LiveView (server-pushed, no client polling).
• Legal-move validation, turn handling, and win detection.
• Live game feedback in the UI.

How it works

Game state lives server-side and is pushed to both connected clients over LiveView's websocket, so a move made by one player appears on the opponent's board with no refresh.

• The player who creates the game gets the white pieces.
• Joining a game is just opening the shared /game/:game_name URL in another browser.

Tech

• Elixir (1.12+) / Phoenix / Phoenix LiveView
• Server-rendered, real-time UI — no separate JS frontend framework.

Hackathon constraint: no dependencies beyond those in mix.exs were allowed. That meant no off-the-shelf chess library — move generation and validation are implemented from scratch in Elixir.

Running locally

# Requires Elixir 1.12+ (asdf recommended)
mix deps.get
mix phx.server

Open two browser windows at http://localhost:4000, create a game in one, share the URL to the other, and play.

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_{Originally built from Doofinder's provided Phoenix chess template during the Oct 2022 code challenge.}