How to use Unknown to build and playtest a Godot game
The demo agent built and launched Reversi, played four moves and corrected invalid cell selections after inspecting screenshots.
news.ycombinator.comPrompt to try
Editorial adaptation, not the source author’s exact prompt. Replace bracketed inputs and review tool permissions first.
Build [Reversi variant] in [Godot project] using the connected MCP tools. Implement [rules], [rendering] and [UI]. Launch the scene and playtest it yourself with simulated clicks. Take screenshots after each move, inspect score changes and board highlights, and correct invalid moves.
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See placements →What happened
The demo agent built and launched Reversi, played four moves and corrected invalid cell selections after inspecting screenshots.
Reported by y1uda on Hacker NewsHow the agent did it
- Received a Reversi prompt specifying rules, rendering, UI and self-playtesting.
- Wrote about 200 lines of GDScript and built the scene.
- Launched the game and clicked cells to play four moves.
Where a person stepped in
The author supplied the game prompt; the post does not describe a separate human review of the demo output.
A person set the goal and reviewed the result.
The author built a Godot MCP server to close the gap between generated code and testing a running game. Their previous workflow required a person to run the game, inspect it and report back. The new server exposed tools for launching scenes, simulating input, taking runtime screenshots and inspecting live state.
In the reported demo, an AI received one prompt describing Reversi rules, rendering and UI, with an instruction to playtest the result. It wrote about 200 lines of GDScript, built the scene and launched the game. It then played four moves by clicking cells, taking a screenshot after each move to verify what happened.
The third and fourth moves initially targeted invalid cells. The agent detected that the score had not changed in the screenshot, read the board highlights to identify valid moves and corrected its choices. This provides a specific example of the server supporting a build-test-correct loop. The post lists Claude and Cursor as compatible clients, but does not identify which client ran the demo. Mutations use Godot's undo manager.
Who it's for: game developers who want an agent to inspect and interact with its own Godot output.
Prompt
Suggested prompt (written by Agents In Use, not the author's)
Source: Hacker News · y1uda
Frequently asked questions
How did the agent detect invalid moves?
The screenshots showed that the score did not change. The agent then read the board highlights to find valid moves and corrected its cell selections.
Which tools enabled runtime playtesting?
The server includes play_scene, input simulation tools, get_game_screenshot and tools for inspecting the running scene tree and node properties.
More details
Remaining steps
- Took screenshots after moves to verify the game response.
- Detected invalid moves and used board highlights to correct them.
About this account
The demo agent generated the game and performed its own runtime playtesting and move correction.
Platform: Hacker News. Attribution: https://news.ycombinator.com/item?id=47137589. Prompt: Suggested (written by Agents In Use, not the author's). Sourced by the Agents In Use pipeline.
Credit: y1uda on Hacker News
Source published 24 Feb 2026
Source checked 14 Oct 2026
Tools and topics
Godot · Godot MCP server · GDScript · Node.js
Godot · Playtesting · MCP
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.