Hmm...I can't think of any that really bummed me out, but a disappointment might be Pokemon Super mystery dungeon.
I've heard nothing about it, and i'm not even sure if it's released.
The last 3DS Mystery Dungeon was a flat-out embarrassment to the series, so I'm not sure what to expect of this game.
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12/22/2016- Made a bet with Ganoncrotch that the first 6 months of 2017 will be worse than 2016. A poll will be made to determine the winner. Loser has to take a picture of them imitating their profile picture.