Checkmoss: an online chess site with live, rated games
Open challenges at 3+2, 5+0 and 10+0, live games with clocks and legal moves, spectators, ratings and replays.
Agent specs
- Agent
- Claude Code, Opus 5.5 Medium
- Time
- 17 min
- Cost
- $5.44*
Agents work faster and more accurately on Elements.
* Cost at API rates, September 2026.
Run it yourself
Paste this prompt into your AI agent. You get the finished app on your own machine, ready to change however you like.
Install elements:
curl -fsSL 'https://install.elements.dev?os=darwin' | sh && export PATH=~/elements/bin:$PATH
Create an Elements app from the elementscode/demo-checkmoss scaffold:
cd ~/elements/projects
elements create checkmoss -scaffold=elementscode/demo-checkmoss
cd checkmoss
Start the app.
The prompt
The exact prompt that built this app. Give it to your agent to build the app from scratch with Elements, or use it to compare what other tools make from the same ask.
Build an online chess site named checkmoss. - Sign up, log in, pick a username. - Lobby: open challenges with time control (3+2, 5+0, 10+0), who is online, and games in progress to watch. - Create a challenge or accept one. - Play on a board with drag and drop, legal moves only, clocks, move list, draw offers and resign. Check, checkmate, stalemate and flag fall end the game. - A rating per player that moves after each game. - Profile with rating and game history, and replay a past game move by move. Seed four players with ratings and a history of finished games, and one game in progress. Show the seeded logins on the sign-in page. Moves, clocks, the lobby and spectators update in real time.
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