Nintendo has released the demo version of Brain Age: Concentration Training, known as Demon Training in Japan, in the Nintendo eShop on Nintendo 3DS. The demo is free to download and requires 391 blocks. The full version of the puzzle video game, which features ‘devilishly difficult’ brain-training exercises that are supposed to help players improve their concentration skills, will be released at retailers and in the Nintendo eShop on February 10th in North America.