The game development team at design firm Ustwo is sorting out how to add new levels to its surprise hit Monument Valley as the premium mobile puzzle game climbs past 1.4 million downloads. This is intriguing from a game development perspective because Ustwo says it initially had no plans to return to the game. Monument Valley was designed to be a complete experience, but the team had to figure out how to slot in new content after the game took off and fans started asking for more. Their solution? Next week the company will release Forgotten Shores, a pack of eight new levels that slot into the game's level progression and can be purchased from within the Monument Valley for $2. "It's kind of like a directors cut," executive producer Dan Gray told Wired. "Like watching the bonus features on a DVD." Ustwo initially designed Monument Valley to appeal to a broad audience, drawing inspiration from architecture and the "impossible building" designs made popular by artists like M.C. Escher. If you'd like to know more, lead designer Ken Wong explains the game's creation in his own words during this talk from GDC Europe 2014.