Brain Game.....the site is in Japanese so here are the instructions:

1. Touch 'start'

2. Wait for 3, 2, 1 countdown after which numbers appear

3. Memorize the number's position on the screen, then click the circle from the SMALLEST number to the BIGGEST number eg 0359.

4. At the end of game, the computer will tell you the age of your brain.

Here is a link that might be useful: Brain Game