Pretty neat :)

Please note that the registerElement API is deprecated and browsers are implementing the V1 API, window.customElements.define().

This proof of concept for the homepage is merely a showcase of a technology, but in rot.js, we might actually offer a full-blown custom component <rot-display>, a HTML wrapper for ROT.Display. Not sure if worth it though, as this is probably the only part of rot.js that has a meaningfull custom element.