If you buy this game (or another in the offer) you can get the following:
Devillish Brain Training – £12.99 down to £6.49
Paper Mario Sticker Star – £12.99 down to £6.49
The Legend of Zelda Tri-Force Heroes – £7.99 down to £3.99
Metroid Prime Federation Force – £5.99 down to £2.99
Captain Toad Treasure Tracker – £7.99 down to £3.99
Yo-kai watch (or whichever game you chose) stays the same price and one of the ones listed about goes down to half price at the prices mentioned, even if they are more expensive.