This looks like a good deal, but is limited in numbers. Tetris DS has been reduced to £14.99, but is only available in-store (reserve and collect)
Also, with any DS game you can pick up a DS stylus kit for half price - £4.99 - which includes a hard case and 5 stylii (?!)
That makes it £19.98 for Tetris, a hard case and 5 Styluses (?!)
You might want to pair the stylus kit with another DS game if Tetris sells out - if, like me, you are always loosing the things down the back of the sofa.