🧠 Symmetry Sin (Illegal Move Exercise)
24 February 2026

🧠 Symmetry Sin (Illegal Move Exercise)

Chess Visualization with Aiden Rayner

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Illegal Move Exercise: The audio will lead you through a series of moves from the beginning of a game. Somewhere in there, a player will make an illegal move but the game will continue anyway. Find the illegal move.



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PGN for today's exercise:




    c4 e5 2. Nc3 Nc6 3. g3 g6 4. Bg2 Bg7 5. d3 d6 6. e4 c5 7. Nf3 Nf6 8. 0-0 0-0 9. Be6 Nd5 *


And the answer is...

Black's move 6... c5 is illegal because the pawn is blocked by the Knight on c6.