Portugues
Queen Sac
Saved games stay in this browser only.
About the game
Queen Sac pits you against Stockfish, the strongest chess engine in the world, with one crucial change. This Stockfish has been modified: if it has any move that lets you capture its queen, it must play such a move. A strong engine that is not allowed to protect its queen when it has a way to lose it is a very different opponent.
You play White, with the usual rules and a normal board. Most of the time the engine just plays good chess, and you will be under pressure. But the rule creates a trap you can use. Whenever you can arrange a position where one of its legal moves hangs the queen, the engine has to take that road, whatever it thinks. Your job is to make the pieces stand so that the forced sacrifice happens, take the queen, and finish the game with the material you have won.
Playing it here
Click Play, press Start and then Begin. The engine runs inside the page, so its first move can take a moment; no game data is sent anywhere.
Controls
| Input | Action |
|---|---|
| Click or tap a piece, then a square | move the piece |
| Resign button | give up the game |
A few things worth knowing
Think about the rule, not the engine. The point is to find a position in which one of its moves loses its queen.
Keep your own king safe. The engine plays well in every other respect and punishes loose play.
It is a puzzle as much as a game. Take your time and look at which moves the rule forces.
Questions
Is it really Stockfish? Yes: it is Stockfish with the added rule, running in your browser in a single thread.
Does it work on a phone? Yes, tap a piece and then its destination.
Credits and licence
Queen Sac was made by dtsudo and is published under the GPL-3.0; it is a front-end for the author's Queen Sacrifice Bot. It uses Stockfish through Stockfish.js (GPL-3.0) and chess.js (BSD-2-Clause) for the rules. The chess pieces are by Cburnett (BSD), the images and sound effects of Kenney are CC0, the fonts (Roboto and a font from metaflop) are under the SIL Open Font License, and the music "Happy Arcade Tune" is by rezoner (CC BY 3.0). The licence texts are in the licence file linked from this page. The Stockfish.js engine (GPL-3.0) is served as published by the game's author; its source (stockfishSourceCode.zip) is hosted here. The neural networks embedded in its .wasm are not part of that source: the build scripts in it download them from tests.stockfishchess.org, where they are published under the same GPL-3.0 terms. We changed three things: a policy that stops the page from loading anything from other sites, the link to the author's GitHub page (it does nothing here), and the browser-save keys, which get a prefix so they do not clash with other games.