It's important to note that this app is not a game, but a scorekeeping utility for a card game. To use this app, you need a deck of cards, and three friends. Detailed instructions for playing the game can be found at https://github.com/tcsauter/thirteen/blob/master/README.md.
Furthermore, if you're familiar with Github, and you decide to look around at the link above, you'll see that all of the source code for this app is available. I built this app as a way to practice different concepts I was learning in Android development, and I will continue to build on it, as I learn new concepts and determine whether I can apply them to this app, and how. As such, I won't monetize it in any way, and I've decided to keep it open source. Please feel free to clone any branch of the repository and adjust as you like. Or, preferably, suggest updates to me, or collaborate with me via Github as you make changes. I would love to see what people come up with, and be as involved as I can!
Enjoy, and let me know your thoughts! I'm aware of some bugs that will need to be ironed out in future releases, but please email me or let me know in your ratings as you find them. You may find some I'm not aware of.