About a year back I wrote my first XNA game for Windows Phone. The game is called Bizzy Bees and you can download and play it for free from the Marketplace.
The idea of the app is quite simple… the goal is to collect as many rainbow flowers as you can before all the flowers hit the bottom. You collect flowers by matching flowers and bees, so a yellow flower matches with a yellow be, a pink flower with a pink bee etc. and all bees match up with rainbow flowers.”, Tess Ferrandez, MSDN. Direct Link