Nintendo announced yesterday that Touch Generations flagship title Brain Age has surpassed 4 million units sold worldwide.
By territory, the title has sold 3 million in Japan (where it piggybacked on an already-existing brain training phenomenon there, personified by Dr. Ryuta Kawashima, to great success), 600,000 units in the United States, and 500,000 units in Europe. The title has also shown tremendous longevity on the charts, still showing up on Japanese charts 15 months after its original launch.