
Each week, Apple chooses an "App of the Week" to highlight, which means it can be downloaded for free. This week's pick is an iMessage app called Checkmate, able to be played with friends using Messages.
Checkmate is one of the first iMessage apps to be named App of the Week, and it is normally priced at $0.99. With Checkmate, you can play a game of chess with a friend entirely over iMessages. Apple's notes on the game:

Starting up a game with Checkmate requires you to go to the App Drawer and select the Checkmate icon. From there, updates on moves in the game are sent using iMessages. Checkmate can only be played within iMessage and it needs to be installed through the Messages App Store.We use iMessage for everything from keeping up with family news to sending stickers to our significant others. Sometimes, though, we just want to duke it out with knights and kings on the chessboard. What makes Checkmate so great -- aside from its super-intuitive interface -- is the way we can chat with (and smack-talk) as we play... or take as much time as we need to contemplate our next move.
Checkmate supports multiple matches, so you can play with multiple people at one time, across all of your devices. Checkmate has no in-app purchases and regularly adds new themes for free.
Checkmate can be downloaded for free for the next seven days. [Direct Link]
Article Link: iMessage App 'Checkmate' Available for Free as Apple's App of the Week