A fourth RuneScape game is under development using Unreal Engine
Jagex says it will reveal more details about the game, tentatively named RS4, next year.
Reports & sources
Polygon
RuneScape 4 Officially Revealed by Jagex (opens Polygon)Polygon's feed description
Engadget
A fourth RuneScape game is under development using Unreal Engine (opens Engadget)Engadget's feed description