As the game advances, the gameplay itself steadily evolves at the same time, the levels and puzzles gradually becoming more complex and multi-layered. Levels begin taking place over multiple rooms at once and eventually ventures into an outside world beyond locked buildings. In later levels, the player acquires a device called the "Manipulator of Time and Space" (MOTAS) "device", which takes the player back to previous levels via time travel in order to retrieve items; the player then returns to the current level to solve the puzzles using the items retrieved.