From Cocoa Stuff:
A beautiful and elegant chess application for the casual player. John Gruber of Daring Fireball: "Without question the best iPhone chess game". Playing chess has never been a more pleasant experience. On any platform. Everything is beautifully rendered; from the board and pieces to the way they animate. Deep Green for iOS is the successor to the multi-award winning Newton version. If you like Deep Green, please rate it on the App Store. FEATURES: Play against engine or human, or engine vs. engine. Adjustable engine strength. Concentration setting allowing the engine to play more like a human. Manual board setup. Game playback (first/previous/next/last position, auto-playback, drag slider). Replay of last move. Move suggestion (animated on board). Take back (undo, all the way back to start). Free choice between tap/tap and drag/drop moving (no need to set preference). Display of captured pieces. Smooth animations everywhere. Game and state saved between program sessions. Rich, analog-type sounds (optional). Callout notification for check, stalemate, and checkmate, (optional). Vibration on check, stalemate and checkmate, (optional). Board coordinates (optional). Board auto-rotation (optional). Clean and beautiful user interface. Two built-in skins. And more.) Vibration is only available if the iOS device is capable of it.