How 2004 RuneScape fit a multiplayer RPG into 56k dial-up

In 2004 I played too much RuneScape on a 56k modem that died the moment Mum picked up the phone. A 3D world, up to a couple of thousand players on a server, dozens on screen at once - in the browser, on 5 kilobytes per second. It worked. Let&rsquo;s follow a single step and see how.