Welcome to Niel's Chess
A quantum chess adventure for curious minds—10 to 99 and beyond.
I. Play online
Click here to play—see instructions below.
Show instructions
Main Niel's Chess moves:
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Simple move: click 1) your conventional or indefinite piece, then 2) a reachable square.
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Superposition: click 1) one or two unoccupied, reachable squares, then 2) your conventional piece.
- Click repeatedly on the square(s) selected in step 1 to arrange an unequal superposition.
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Entanglement: click 1) an unoccupied, reachable square, then 2) an opponent's indefinite piece, then 3) your conventional piece.
- At least one of your newly added indefinite pieces must attack the opponent's indefinite pair selected in step 2.
- The color on the square of step 1 will match that of the indefinite piece of step 2.
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En passant: click 1) your conventional or indefinite pawn, then 2) the opponent's pawn piece that has just advanced two squares.
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Tunneling: click 1) your conventional piece, then 2) an unoccupied square right behind an opponent's conventional piece.
Additionally, if B/W-Hadamard is checked for your side:
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Z move: click twice on your non-entangled indefinite piece with a blue mark.
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Hadamard: click 1) your non-entangled indefinite piece, then 2) its pair piece.
Options to reduce complexity:
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3-Max: each player may have up to 3 indefinite pairs on the board, and there may be up to 1 entangled group.
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Slowdown: all superposition moves must be of the 'stay & move' type.
II. Rulebooks
Main rules - EN, DE, HU, FR, IT, ES, PT, CN, JP
↳ Video rulebook (+ quantum physics): EN
Hadamard game - EN, DE, HU
Poker style - EN, DE, HU
Notes:
- Both players act as observers whenever the superposition state of a piece collapses. The position on the chessboard reflects all knowable spatial information.
- The concept of “collapse” is left open to interpretation—such as objective collapse, observer-induced collapse, or apparent collapse due to decoherence.
III. YouTube videos
Explaining the rules + playing a game (with OrcaChess)
Niel's Chess for education (AI for Good, ITU / UN 🇺🇳)
IV. Publication
T. Varga, Niel's Chess: A Quantum Game for Schools and the General Public
2024 IEEE International Conference on Quantum Computing and Engineering (QCE)
Montreal, QC, Canada, 2024, vol. 3, pp. 53-60
V. How to buy
Visit our webshop.