Tic Tac Toe

Phase one: place three pieces

X begins. Players alternate selecting empty squares until each side has placed three pieces or somebody wins. A center move participates in four possible winning lines, a corner participates in three, and an edge participates in two. That makes the center useful, but a coordinated corner plan can still create two threats.

Phase two: move your pieces

Once a player has all three pieces on the grid, their next turn requires a move. Select one of your symbols, then select any empty square. Movement is not limited to adjacent cells. The win check runs after every move, so both the square you enter and the line you leave behind matter.

With a keyboard, Tab moves through the nine square buttons and Enter or Space activates the focused square. Select one of your pieces first, then activate an empty destination. Each button announces its row, column and current symbol.

Solo and local play

In VS AI mode, the computer takes an immediate win first. During placement it blocks an immediate X line, then values the center and corners. During movement it rejects moves that give X an immediate winning reply when a safe alternative exists. 2 Players keeps both turns on the same device. Switching modes resets the board so the rules never change mid-round.

Strategy for this variant

• During placement, build two connected pieces that can threaten more than one destination.
• Before moving, check whether removing the selected piece exposes an opponent line.
• Force a response by creating a line with two possible finishing squares.
• Track all six pieces; unlike standard Tic Tac Toe, occupied squares can become available again.

Two-part check: identify the threat created at the destination and the defensive line abandoned at the starting square before committing a move.

Why the center is useful but not sufficient

The center belongs to four winning lines, compared with three for a corner and two for an edge. That makes it flexible during placement, but a center piece can become pinned by its defensive job. Moving it may open a row, column or diagonal for the opponent.

A good three-piece shape has more than one useful future destination. Two adjacent pieces plus a third that blocks the opponent usually create more options than three pieces that depend on a single empty square.

Read the movement phase as a loop

Because any piece may move to any empty square, the board can repeat. There is no automatic repetition draw in this version; the round continues until a line is formed or the player restarts. If two players circle through the same positions, agree to restart rather than treating the session counter as a forced result.

The X and O win counters are local to the open page and reset when the mode changes or the page is reloaded. No nickname, server request or public leaderboard is involved.