Raph Koster

The virtual-world theorist of MMORPG design. Koster led the design of Ultima Online — the game that proved persistent worlds could work at scale — then served as creative director of Star Wars Galaxies, the sandbox whose player-driven professions and economy are still the genre's reference point. His book A Theory of Fun for Game Design is a standard text, his blog at raphkoster.com is twenty years of design writing in public, and his studio Playable Worlds is now shipping Stars Reach.

Designed the two sandboxes — Ultima Online and Star Wars Galaxies — that every 'player-driven world' since has been measured against, and never stopped publishing what he learned.— MMOlist Hall of Fame citation