Download

Take the simulator with you. The download is for running offline — on a machine with no internet connection, or one where you would rather not depend on this site being up.

Download Reactor Dynamics (.zip)

You do not need this to play. The simulator runs in your browser right now, and that version is always the current one. The download exists for when a browser tab is not what you want.

What you get

A zip containing one HTML file. Unzip it, double-click it, and the whole simulator opens in your browser — the plant, the control room, the operator's manual, the training missions, all of it.

There is nothing to install and nothing to run alongside it. No server, no Node, no Python, no extensions. It does not connect to anything: once the file is on your machine, it never needs the internet again.

Keeping it current

The offline file is a snapshot of this site at the last deploy. It does not update itself. For the latest build, download again from this page — or just use the online simulator, which is always current. What changed is in the changelog.

If it does not open

• Unzip it first. Opening the HTML from inside the zip viewer will not work — Windows and macOS both hand the browser a temporary copy that behaves unpredictably.
• Use a current desktop browser. Firefox, Chrome, Edge and Safari are all fine. Desktop is the design target; phones and tablets are not supported.
• Saved games stay on the machine that made them. The offline copy keeps its progress in that browser's local storage, separately from this site.