Dune II ported to the Web with Emscripten
I'm sure this site will be taken offline for copyright infringement almost immediately, but it really is a decent recreation of the original. It's also historically significant: Dune II is to the real-time strategy genre what Wolfenstein 3D is to the first-person-shooter: not necessary the very first example ever, but the first to achieve notable popularity, and the progenitor of most of the following examples.