Digit span PLAY is the game.
You should input the numbers that the navigator read out.
Make your working memory excel.
Don't make memos.
Navigators :
HATSUNE MIKU (English, Japanese)
LUO TIANYI (Chinese)
SeeU (Korean)
YUDUKI YUKARI (German)
MEIKO (Russian)

EULA
http://www.fujiu.jp/AndroidApp/app010_digitspan/digitspan_eula.html