Nintendo's handheld puzzle series Professor Layton has reached 11.47 million worldwide shipments across four titles, developer Level-5 has revealed. AndriaSang reported the series passing the 11 million milestone. The DS-only series has proven popular with both traditional and so-called casual audiences, and has been the subject of mainstream TV ads from Nintendo. A fifth game, Professor Layton and The Miracle Mask, will be a 3DS launch title.