macOS
your platformmacOS 11 or later · arm64 & Intel
Signed with a Developer ID and notarized by Apple, so it opens with no Gatekeeper warnings and updates itself in place.
Download Hearth
The app for building games with a coding agent. The current release is v1.9.0. Free and open source under MIT. Bring the agent you already use.
Choose your platform
Windows
your platformWindows 10 or later, x64
Not code-signed yet, so SmartScreen warns the first time you install: choose More info, then Run anyway. Updates the app applies itself never show it.
Linux
your platformx86_64
Mark the AppImage executable before the first run: chmod +x Hearth-linux-x86_64.AppImage. The .deb installs the usual way.
Older versions, checksums, and the standalone files live on the
GitHub releases page.
Prefer building from source? git clone and
npm run app, see the
desktop app guide.
Installed macOS and Windows builds, plus the Linux AppImage, check for updates automatically. Portable zip builds and older unsigned macOS builds update by downloading the latest release from this page.
Playtest from a terminal
This is what the agent reaches for when it checks its own work, and it runs perfectly well without the app. Put it in a build script, or hand it to an agent working in a terminal. It writes its report to the same place either way, so everyone reads the same thing. A failed playtest fails the command, which makes it safe to gate a deploy on.
Needs Node 20 or newer and a copy of Chrome. Each release attaches it as a single file, and inside the app's terminal it is already on the PATH. The command-line guide covers both routes.
hearth-probe sweep . claude mcp add hearth-probe -- node hearth-probe-mcp.mjs --project <your game> The first line plays a game in the current folder. The second lets Claude Code, Codex, or any MCP client run the playtests itself.