It's taken some time, but finally the in-app purchase element of trading card game Arena 9 has gone live.
The game itself is based around a relatively simple playing system.
Each of the five character cards in your hand has a number (one to nine) on each its four edges. Lay down a card with a higher number adjacent to your opponent's on the 3 by 3 grid and that card turns your colour.
iPad version on the way too.