The items offered through the My Nintendo reward program tend to have expiration dates. You can only redeem them up until a certain point, and then they’re pulled from the site. My Nintendo Picross: The Legend of Zelda: Twilight Princess, the only game you can get with Platinum Points, was originally going to be removed from the program on October 1, 2016. Nintendo has now eliminated the expiration date in all regions.
My Nintendo Picross: The Legend of Zelda: Twilight Princess is immediately available for the Nintendo 3DS. It costs 1,000 Platinum Points and offers 45 The Legend of Zelda-inspired puzzles that can be played in Picross and Mega Picross modes.