This is a quick project built with Node.js. It uses the public API at hlkz.sourceruns.org, and my fork of the project hlviewer.js which lets you view Half-Life maps and demos in the browser. I modified it to support the replay format used on the multiplayer KZ/bunnyhop servers, and add a keys-pressed display. You can see the full set of changes here.

Check it out using the demo link above or click repo see the code on GitHub.

You can also see a demo of the player embedded in my related blog article, Clustering Half-Life movement maps — an exploration of what insights can be extracted from the replay data.