Really Bad Chess for iPhone
There are plenty of awesome chess apps available for iOS and Android. Not everyone is interested in taking on Stockfish and other top engines. Really Bad Chess makes the game fun even if you are not an experienced chess player. It comes with random pieces to keep the game interesting.
The app has an AI to challenge you and improve your game. You can think of it as Chess960 but with even crazier setups. The rules of the game stay the same though. You can download the app for free.