An occupied tic-tac-toe square cannot be overwritten, converted, or used for another legal move. Tapping an existing O does not place X there. First check whether the square is empty and whether the round is still active; a rejected occupied-square input does not grant another mark or erase the opponent’s reply.
0 of your turns · 0 of 9 cells occupied
Game paused.
Select Continue whenever you are ready.
Press Tab to enter the board. Use arrow keys, Home, or End to move focus; Enter or Space selects a cell. Escape pauses.
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You play X against a local computer playing O. Choose an empty cell to place X; the computer then replies. Connect three marks horizontally, vertically, or diagonally. If the board fills with no line, the result is a draw. Arrow keys move focus; Enter or Space selects a cell. The computer uses a complete search, so perfect play can draw rather than guarantee a human win.
The board has nine locations, and each legal turn places one mark in an empty one. Once X or O occupies a location, it remains that side’s mark until the board is replaced through the game’s reset or new-round action. The game does not use capture, swapping, or stacking rules.
This matters when a square you intended to use becomes occupied after your previous choice. In the main mode, you play X and the local computer replies with O when the game is still in progress. The board you see after that reply is the position for your next decision. A square that was empty before O moved may no longer be an available destination.
Suppose the center contains O. Selecting the center again does not remove it, make it X, or use a turn to pressure that mark. You need an actual empty square that blocks a line or develops a legal possibility. Repeating the same unavailable input cannot make a different game rule take effect.
Likewise, selecting one of your own Xs does not create an additional X in that square. Three marks must occupy three different locations in a complete row, column, or diagonal. A count of repeated taps is not a count of marks. Before looking for a software fault, compare the square’s existing symbol with the action you expected it to accept.
A focus outline helps you see where keyboard input is directed. It does not necessarily mean an occupied location can accept another mark. Look at the symbol inside the square as well as the outline. On a phone, confirm the exact cell boundary before touching near neighboring marks.
If the target you intended was an adjacent empty square, choose that square explicitly rather than continuing to tap an occupied neighbor. A selection mistake and an illegal move are different explanations for an unchanged board. Neither justifies deleting O or pretending that a mark moved after it had already been placed.
When either side completes a line of three, the round ends. You cannot place an extra defensive mark afterward, even if another location is still empty. If all nine squares are full without a winning line, the result is a draw and there is no tenth square to use.
Check the result before diagnosing every unchanged input as an occupied-cell issue. A game can be finished while several empty cells remain after an early win. The relevant restriction is then the end of the round, not a requirement to fill the whole grid. An explanation should preserve the final line instead of adding hypothetical turns the rules no longer allow.
Use the confirmed reset or new-round action when you actually want an empty board. That decision is different from trying to revise one old square. Read the confirmation rather than clearing a position you wanted to study. Pause lets you step away while retaining the current context; it does not make an occupied square editable on return.
Local saving depends on the browser retaining the game’s data, not on a shared online account. When resuming, inspect existing marks and the current result before choosing an empty square. The main opponent remains a local computation, not another person you can ask to withdraw a move through the board. Understanding occupancy gives you a clear distinction between an unavailable square, a finished round, and a position that is ready for your next legal action.
No. Occupied squares remain fixed for that round.
No. A legal mark requires a different empty location.
No. A focus outline identifies navigation; existing occupancy and game status still determine legality.
The round may already have ended with a winning line; empty space alone does not keep it active.
No. Pausing preserves the position; a confirmed reset replaces the round instead.