In a few days two different versions of Tetris will be removed from the Eureopean 3ds e-shop . The 2011 version of Tetris for 3DS ( Tetris Axis in the USA ) is the first game to be taken off the European 3ds e-shop come January 1st 2015.

The second version of Tetris being taken off the European 3DS e-shop is the 1989 game boy original (virtual console ) version of the game.

I'm not sure to why these games are being taken off the e-shop in Europe, or if this will apply to other 3DS e-shops across the globe too. So you have a few more days (rest of the year ) to pick up these games from e-shop if you want them.

UPDATE: January 1st 2015

These games have also been removed from US e-shop

Tetris ® & © 1985~2015 Tetris Holding. Tetris logos, Tetris theme song and Tetriminos are trademarks of Tetris Holding. The Tetris trade dress is owned by Tetris Holding. Licensed to The Tetris Company. Game Design by Alexey Pajitnov. Original Logo Design by Roger Dean. All Rights Reserved. Sublicensed to Tetris Online, Inc. Published by Nintendo. Nintendo 3DS is a trademark of Nintendo. © 2010-2015 Nintendo.

http://www.nintendoworldreport.com/news/39304/various-versions-of-tetris-being-removed-from-eu-3ds-eshop