3D Tic-Tac-Toe
Get four in a row anywhere in a 4×4×4 cube.
How to play 3D Tic-Tac-Toe
3D Tic-Tac-Toe takes the classic game of Tic-Tac-Toe into a cube. The board has four layers, and each layer is a 4×4 grid, so there are 64 cells in all. A plastic version of this game was sold as Qubic, and computers learned to play it very early on. Two players, X and O, take turns. X goes first.
Goal
Be the first to get four of your marks in a straight line. There are 76 possible lines:
- rows, columns and the two diagonals inside any one layer,
- straight down through the same cell of all four layers,
- slanted lines that drop one layer per step, along a row, a column or a diagonal,
- the four long diagonals from one corner of the cube to the opposite corner.
Turn by turn
- On your turn, tap or click any empty cell in any layer to place your mark. Marks never move.
- In 3D view, the four layers are stacked like floors of a tower: layer 1 is on top. Point at a cell and the same spot in the other layers lights up, which makes vertical and slanted lines easier to see.
- In Flat view, the four layers sit side by side as four small boards. This view is easier to tap on a phone. Switch views at any time with the View menu; the game goes on.
- With a keyboard, use the arrow keys to move between cells (Up and Down walk through all layers), Page Up and Page Down to jump a layer, and Enter to play.
End of the game
The game ends as soon as one player has four in a row; the winning line is drawn through the cube. If all 64 cells fill up with no line, the game is a draw, but that is very rare.
Playing the computer
Easy blocks some of your lines and wanders. Medium blocks every threat and spots short attacks. Hard searches chains of forcing threats and is very hard to beat. The status bar warns you when your opponent has three in a line.
Strategy tips
- Take the strong cells. The 8 corners of the cube and the 8 cells in its centre each lie on 7 lines. Every other cell lies on only 4. Early in the game, these 16 cells are worth the most.
- Think in forcing moves. A line of three with the fourth cell empty must be blocked at once. Chain such threats so that each block helps you build the next one.
- Win with a fork. The goal of a chain is a move that makes two threats at the same time. Your opponent can only block one of them.
- Watch the hidden lines. Vertical and slanted lines through the layers are the easiest to miss. Point at a cell in 3D view to see its column light up.
- Block with tempo. When you must block, pick the block that also adds to one of your own lines, so your opponent has to answer you next.
3D Tic-Tac-Toe FAQ
How many ways are there to win in 4×4×4 tic-tac-toe?
There are 76 winning lines: 48 straight rows, columns and verticals, 24 diagonals that lie in one flat slice of the cube, and 4 long diagonals from corner to corner.
Is this the same game as Qubic?
Yes. Qubic was the name of a 4×4×4 tic-tac-toe set sold in the 1960s. The rules here are the same: four in a row in any direction wins.
Can the first player always win?
In theory, yes. Computer studies have shown that the first player can always force a win with perfect play. The winning plan is very long and hard, so real games are wide open.
Which view should I use on a phone?
Flat view shows the four layers as four boards side by side, with bigger cells that are easy to tap. 3D view shows the cube as a stack and makes lines through the layers easier to see.
