Well there is so much you can do in a brain age game. Surely people have trained their brains enough lol.

Also I wasn't aware that their was a new Brain Age game lol

To be fair, Brain Age games are developed in Japan by Nintendo, not iOS or Android developers.  And it's not like it's ever been a full-price series.  The DS versions ran for $19 or less a pop.  I think Nintendo is charging $30 for this new 3DS one.  Probably why the game hasn't sold well.  $30 is a lot for brain training exercises.

To be fair, guys, this game has sold copies, it's for whatever reason not being tracked by VGChartz. If you look at Media Create/Famitsu sales from last July, the game sold over 100k copies in just a week or two, and that doesn't include digital sales, for which Iwata said there were a lot due to the nature of the game.

In the west, I assume the game bombed hard. 3DS owners in the west are not the same as DS owners. The world's a different place.

Clearly the first 35 million were successful in accomplishing what they set out to do ...

exactly.  My brain is the one that makes the "game" work, so really, why the hell would I give them $30 for somethin I AM DOING?!   At most it should be 20.    

OUCH! Such venom...I am truly hurt by your internet insult.

The game isn't out yet in Europe. Has it been released in the US?

In general: It's because the market was over saturated with Brain Age clones: We had English Training, Eye training, Big Brain Academy, countless of Ubisoft games and even games with the same name on PSP. It's the same thing that happened to Guitar Hero! The genre / IP didn't suddenly implode like the OP suggests. It was a slow decline caused by a truckload of rip-offs.

Ok, so Brain Age train wrecked. Same thing happened to Nintendo Dogs (although not as much).
What is the problem?
This is not the first time I see you doing this and I will expect more when time goes. Can't wait for your Wii Fit U thread!

Now that's false.  Nintendo's success in the 7th generation was nothing more than an aberration, a fad that Nintendo's fans will cling onto while the company fails to reach those heights again.

Nintendo took their eyes off of the casual base it attracted with DS/Wii and now they are well catered too, in fact, overwhelmingly catered too, on iOS/Android. It's completely illogical now to buy a 3DS for Brain Age when dozens of similar games are cheap/free on the phone you already own.

This is a big problem for Nintendo who has long gotten rich off of easy to make games with long selling appeal. But all easy to make games can now be had for next to nothing on phone/tablets. Consoles both home/mobile are only worthwhile for deep, expensive and expansive games that phone/tablets can't provide. Find for 3D Mario/Zelda/Metroid but most of Nintendo's franchises would seem more at home on a tablet than a console nowadays. $350 to play NSMBU? Absurd. It'd be a $15 game (at most!!!) on tablets/phones. Brain Age? $5 - max. People's perception of the value of these games has alterred and Brain Age is a prime example.