a game-tree mystery
mission started — check rows, columns, diagonalsIs going first a guaranteed win?
Going first feels powerful. But does it guarantee a win—or only the first chance to notice a slip? Learn to scan every threat.
A careful player checks before moving
A perfect player checks every row, column, and diagonal, blocks a one-move threat, and takes a win when one is open.
Spot, scan, block
threat appearstwo marks make a threat
threat appearsblock placed
Move through a practice board. A careful reply checks the open winning square before playing anywhere else.
Perfect play closes every door
empty boardempty board
empty boardfull draw
Advance a full practice game. When both sides catch every threat, neither side can force three in a row.
One missed check changes the board
checks one lineone line checked
checks one linechecks every line
Change how carefully O scans a separate practice position. Fewer checked lines leave more immediate chances open.
O just missed one threat
This is a new board. It is X’s turn. Every empty square looks the same—scan the whole grid.
Commit before the new setup runs.
What can X do on the very next move?
Play exactly one X move and watch the board decide.
board after Osame slipped board
board after OX move
