The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Natural Maths:
The Traffic Lights game is a great way to give your child an understanding of place value at the same time as helping them to develop logical thinking.The iPad chooses a secret number and the player has only six guesses to find it. The Traffic Light clues show that the guess has:GREEN: The right digit in the right place of the secret number ORANGE: The right digit, but in the wrong place of the secret numberRED: The wrong digit and so not anywhere in the secret numberThere are three levels, using 4-digit, 5-digit and 6-digit secret numbers. Just as you feel safe at one level, its time to go on to the next.