Gobblet Gobblers-style Strategy: Tips to Win Stack Tic Tac Toe

A size-3 piece is the only piece nothing can cover. If you place both early, you lose your best way to stop a threat and to steal your opponent’s pieces by covering them.

A good rule of thumb is to keep one large piece in your hand. The final block against a line is usually made with a large piece.

The center belongs to four lines (one row, one column and both diagonals), more than any other square. Corners belong to three lines and edges to two.

A small piece in the center is quickly covered and becomes your opponent’s anchor, so take the center with a medium or large piece.

Moving a piece reveals whatever was buried under it. If your move leaves your opponent with three in a row, you lose on the spot. Before moving one of your pieces, always recall what is buried beneath it.

Turning this around, covering an opponent’s piece that sits in their line makes that line hard for them to rebuild. Only you need to be careful when lifting it; for your opponent it is a wall they cannot move.

Covering an opponent’s piece removes one of theirs and adds one of yours at the same time. Covering a piece in your opponent’s threatening line is often better than simply placing a new piece.

If one move creates threats on two lines, your opponent can only block one of them. Pieces in the center or on a corner make it easier to build two lines at once.

If you block a threat with a small piece, your opponent can cover it next turn and complete the line anyway. Block with a piece large enough that it is hard to cover.

This game is generally said to be a first-player win: with perfect play, the player who moves first can always win. In real games perfect play is hard, so the second player can still win often.

To practice, choose to move first in a CPU game and take on Hard. When stuck, ask for a hint to see the best move; if a win is found, it says how many moves it takes. If you slip, use Undo to take the move back.