My 5 year old loves playing the App and really wanted this pack. It worked fine on my ipad Air but not on his Acer tablet. - It uses the camera on the tablet to scan in the code at the base of the karts which then 'magically' get added to the game. The camera on the Acer tablet is in the corner rather than on one of the edges which I think is why it didn't manage to scan it in. My son had also assumed that you get the characters in the karts scanned in too - so was initially dissapointed - but he is now very happy with his new karts.