Here's The Educational But Insanely Fun iPhone Game Everyone Is Playing: 'Threes!'
It's an educational game but highly addictive, particularly for people who like math.
Players must earn as many points as they can by lining up numbered cards.
Connect a '1' or '2' to create a '3'. After that, cards of "3" or higher can only be connected to their doubles.
It costs $1.99 to download for iPhone. Interested in learning more?