You're interested in hosting and developing the HTML5 game Cobalt Calibur with MongoDB, Node.js, and OpenShift. To start, create an OpenShift account and set up your SSH key. Then, follow the guide to create a new application on OpenShift, selecting Node.js as the platform. After setting up the skeleton code for your application, add the MongoDB cartridge to enable MongoDB support. You'll need to install the `rhc` command line utility to start the MongoDB server. Next, download and configure the Cobalt Calibur source code to connect to your MongoDB daemon and bind to the proper IP address and port number required by OpenShift. Finally, commit and push your changes to the server, and browse to the URL for your game instance to refresh and play the game. Note that OpenShift does not currently support websockets, but socket.io will fallback to using long-polling AJAX.