Jagex's browser-based game holds the Guinness World Record for most popular free MMOG, and that popularity seems set to further increase with today's release of an expansion which adds clan citadels to the game's sky. Any clan with five or more members can take ownership of a citadel, and the expansion also introduces the Battleground Editor, which lets clans devise their own multiplayer games, ranging from deathmatches to ball games. Jagex says interest in the update has prompted a rush of new players, with Runescape VP Daniel Clough saying: "Our ambitious plan has always been to make Runescape's clan support the envy of the MMOG world, and we are confident that clan citadels can do just that."