Play-test your own game
A developer built an agentic test harness so an AI could play their game and help with play-testing.
Done with a custom-built or unnamed agent
- What they did
- The game is a browser-based, turn-based crossword dungeon. Claude wrote a node.js wrapper that leaves the game files alone. It adds a text renderer and synthetic key events, served over HTTP. The AI played via curl calls, built fixtures to reproduce bugs, and was told to playtest each milestone feature before moving on.
- How it went
- Milestone 13, with five new special encounters, took 12 minutes and about 120k tokens. The AI caught and fixed a cage bug on its own. Manual playtesting was still needed and found more bugs, but it took under 30 minutes.
- Worth knowing
- It ran on Claude Code with Sonnet 4.6 on the Pro plan; the approach suits text-heavy, turn-based games better than screenshot-driven browser automation.
Try it yourself with Claude Code
Look at my game in [path] and build a test harness that lets an AI agent play it: expose the game state as text or JSON and accept actions like [moves or inputs]. Then have the agent play [number] sessions and report bugs, balance problems, and confusing moments. Finished means a written play-test report with steps to reproduce each issue.
Discussion on HN · Apr 29, 2026
Five of these in your inbox every morning
The best things people got an AI agent to do, each with the prompt to try it.
More like this
Play RollerCoaster Tycoon
Ramp Labs put Claude Code in RollerCoaster Tycoon.
- Custom agent
Test a browser agent on web games
Researchers had ChatGPT Atlas's browser agent play T-Rex Runner, Sudoku, Flappy Bird and Stein.world; it did well on logic puzzles like Sudoku, finishing faster than humans.
Build Godot games with paired design and coding agents
Cowork handles design docs, task queues and playtests while Claude Code writes GDScript and runs Godot and git.
Build a racing game from a single prompt
Codex made a racing game with multiple racers, eight maps and items from one prompt, acting as designer, developer and QA tester by playing it.
Navigate Goat Simulator 3 with a game-playing agent
Gemini-powered SIMA 2 navigates Goat Simulator 3, and a human player can direct it to improve its performance.
Build a minigame collection in a day
A data professional drafted a prompt with ChatGPT and used Cursor agent mode to build a Python tkinter game with four minigames.