Chess is a two-player abstract strategy game played on an 8×8 board with 32 pieces (16 per side). The objective is checkmate: deliver an attack on the opposing king from which there is no legal escape. Recorded in essentially its modern form since the 15th century, chess is the most-played and most-studied board game in the world.
Each side starts with 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns. White moves first; players alternate one move per turn. A move must either place the king out of check, prevent check, or simply develop a piece toward the opposing position. Three special moves — castling, en passant, and pawn promotion — round out the standard rules.
| Piece | Movement | Approx. value |
|---|---|---|
| King ♔ | 1 square in any direction; also castling, once per game | — |
| Queen ♕ | Any distance along ranks, files, or diagonals | 9 |
| Rook ♖ | Any distance along ranks or files | 5 |
| Bishop ♗ | Any distance along diagonals | 3 |
| Knight ♘ | L-shape (2+1); the only piece that jumps over others | 3 |
| Pawn ♙ | Forward 1 (or 2 from starting rank); captures diagonally; promotes on rank 8 | 1 |
King: 1 square in any direction (also castling). Queen: any distance along ranks, files, or diagonals. Rook: any distance along ranks or files. Bishop: any distance along diagonals. Knight: L-shape (2+1), the only piece that jumps. Pawn: forward 1 (or 2 from starting rank), captures diagonally, promotes on rank 8.
A special king + rook move done on one turn. Conditions: neither piece has moved; no pieces between them; the king is not in check; the king does not pass through or land on a square under attack. Kingside puts the king on g-file and the rook on f-file; queenside puts the king on c-file and rook on d-file.
When an enemy pawn advances two squares from its starting rank and ends beside your pawn, you may capture it as if it had moved only one square — but only on your very next move.
Checkmate ends the game with a win for the checkmating side. Stalemate — no legal moves but the king is not in check — ends the game in a draw. A common way beginners throw away winning positions.
For White, 1.e4 leads to open tactical games — try the Italian Game (1.e4 e5 2.Nf3 Nc6 3.Bc4) or Ruy Lopez (3.Bb5). For Black against 1.e4: Caro-Kann (1...c6) or French (1...e6) are solid. The principles — control the center, develop minor pieces, castle early, connect rooks — matter more than memorized lines below ~1500 Elo.
If 50 consecutive moves go by with no capture and no pawn move, either side may claim a draw. The counter resets on every capture or pawn push.
The engine has four strength tiers and three playing styles, and they combine freely — twelve distinct opponents in all. Strength controls how far ahead it looks; style controls what it wants.
| Opponent | Search | What it feels like |
|---|---|---|
| Novice | 1 ply | Takes what it can see this move and misses everything else. It will not hang a rook or queen outright, so games stay winnable rather than absurd. |
| Club | 2 ply | Sees a capture and the recapture. Loses pieces to two-move tactics like forks and skewers. |
| Expert | 3 ply | Punishes undefended pieces and simple tactics. Will not walk into a discovered attack. |
| Master | iterative deepening + quiescence | Deepens until its time budget runs out and extends every capture sequence to the end, so it cannot be tricked by an exchange that only looks good at the search horizon. |
| Style | Priorities | How to beat it |
|---|---|---|
| Aggressive | Piece activity near your king, material in your half of the board. Barely values its own pawn shield. | Trade off its attackers and open a file toward its own exposed king. |
| Positional | Mobility, healthy pawns, the bishop pair, central squares. The classical engine. | Create a locked structure where its extra mobility has nothing to attack. |
| Defensive | King safety above almost everything: castles early, keeps pawns in front of its king, keeps pieces home. | It concedes space. Take the centre, build up slowly, and open a second front. |
Strength and style can be changed in the middle of a game — they only affect the next move the engine searches. Switching sides starts a new game and flips the board so you always sit at the bottom.
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