Chess Plus+ is an enhanced computer chess game powered by a sophisticated artificial intelligence engine resulting in automated opponent player ratings ranging from Novice to Grandmaster!

Computer Player AI Grandmaster Level ELO of 2850+

Includes 4 chess ebooks built-in for offline reading on chess Fundamentals, Strategy, Game Play, and Openings.

With Chess Plus+ you will engage in challenging 1 or 2 player chess games whether you're just starting out or an old pro! Algorithmically varied computer opponent game play simulates real-world match conditions.

FEATURES

Castling, Promotion, and En Passant • Play Black or White • Dual Player Time Clocks • 4 Modes of Play • Scrollable Moves List  • Advanced Artificial Intelligence • 4 Chess eBooks Included • Move Count, Status, and Turn Displays •  Multiple Computer Player Levels • Includes Chess Rules • And more!

Details: https://itunes.apple.com/us/app/chess-plus+/id586035238?ls=1&mt=12

I assume you're the creator of this app, if you want to really grab attention of the mac audience I suggest you program a game analyzer in.
Macs are dreadful when it comes to finding a good chess program with the ability to analyse games, and im sure many people, myself included would be thrilled to have a proficient one.

Chess engines aren't a problem on mac's. Stockfish, Critter and Komodo all have native mac support. The real issue is a good engine GUI like Arena and a full featured database. 

Fear, thank you for your suggestions! This is only version 1 of our app and we do intend to enhance it over time with additional features. Our priority for this version was the Artificial Intellegence aspect for the computer player and we believe that is where the strength of the app lies at this point.

King, good to know!