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

In 2004, RuneScape achieved a remarkable feat by running a multiplayer RPG with thousands of concurrent players on 56k dial-up internet connections by implementing extreme data efficiency measures. The game used a single TCP connection per player, encrypted only the opcode byte of each packet (not the body), and structured all communication around the server's 600-millisecond game cycles to minimize bandwidth usage. This sustained exercise in not wasting bytes allowed a full 3D world with dozens of visible players to function smoothly at just 5 kilobytes per second download speed.