For English speakers, it was the word "blue." Brain Age just didn't like it. But what about for Korean folks? The game just launch there and is apparently having localization issues as well. According to The Korea Times:

The game is supposed to recognize spoken words in some of exercises, but some words rarely register correctly. Also, when you write your answers on the touch screen, the machine sometimes confuses similar Korean words and numbers such as 9 and 0, 7 and 9, and 6 and 0.

Korean readers, we feel your pain. We really, really do. Brian Ashcraft

Korean Brain Age Problems [The Korea Times]

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