Chess

Chess on a board of cream and dark-green marble in a walnut frame, with gold coordinates cut into the rail and ivory and ebony men that cast a soft shadow on the stone. A brass reading lamp burns at one corner of the leather desk mat, a stack of books leans beside it and a wooden clock ticks between the two of you. Tap a man and the squares he can reach fill with gold dots; drag him instead if you would rather. The last move stays lit in gold and a red glow finds the king the moment he is in check.

The rules are all of them. Castling on both wings with every condition checked, capture in passing, promotion with a picker that offers all four pieces, stalemate, the fifty-move rule, threefold repetition and positions where neither side has enough material left to mate. The move generator is proved against the standard perft counts to depth four, so a move that is legal on a wooden board is legal here, and one that is not will never be offered.

The opponent runs in a thread of its own, so the board never freezes while it thinks. It searches with alpha-beta and iterative deepening, orders captures before quiet moves, sits on a few dozen main openings and weighs pawn structure, mobility and how exposed each king has become. Easy glances at the position and moves, Normal takes about a second, and Sharp thinks for two and a half and tends to find the tactic. Play white or black, or pass the device between two players — in face-to-face mode the board turns side-on so both of you see it the same way round and each scoreboard faces its owner. There is an optional clock at 5, 10 or 15+10, undo, a hint, a board flip, the moves listed in proper notation, a game you can export as PGN, and forty hand-made mate puzzles when you would rather solve than play.