Blokus

1 Overview

Blokus is an abstract strategy game for 2 to 4 players designed by Bernard Tavitian and published by Mattel. Each player controls 21 geometric pieces (polyominoes) of one color and takes turns placing them on a 20x20 grid. The critical rule: each new piece must touch at least one of your own pieces, but only corner-to-corner -- never side-to-side. The player who places the most pieces (by square count) wins.

Blokus won the Mensa Select award and is praised for being instantly teachable yet strategically deep. The corner-to-corner rule sounds simple but creates fascinating spatial puzzles as the board fills. It plays in 20 to 30 minutes.

2 Components

• 20x20 grid board
• 84 pieces total: 21 pieces per player in 4 colors (blue, yellow, red, green)
• Each player has: 1 monomino (1 square), 1 domino (2), 2 triominoes (3), 5 tetrominoes (4), and 12 pentominoes (5)

The 12 pentominoes are the familiar Tetris-like shapes. Placing them all is extremely difficult and is the mark of a strong player.

3 Setup

1. Place the board in the center of the table.
2. Each player takes all 21 pieces of one color.
3. The four starting corners of the board are designated starting squares: blue starts top-left (1,1), yellow starts top-right (1,20), red starts bottom-right (20,20), green starts bottom-left (20,1).
4. Blue goes first, then clockwise order (yellow, red, green).

4 Gameplay

On your first turn, place any of your pieces so it covers your designated starting corner. On all subsequent turns, place any remaining piece following the placement rules below. You may rotate and flip pieces in any orientation before placing.

If you cannot legally place any piece on your turn, you must pass. Once you pass, you continue passing every turn for the rest of the game. The game ends when all players have passed consecutively.

5 Placement Rules

Two rules govern placement. Both must be satisfied:

1. Your piece must touch at least one of your own pieces corner-to-corner (diagonally adjacent).
2. Your piece cannot touch any of your own pieces side-to-side (orthogonally adjacent -- up, down, left, right).

Contact with opponent pieces has no restrictions. Your piece can be flush against any opponent piece. The only constraint is how your piece relates to your own existing pieces.

6 Winning

When all players have passed, count the squares remaining in each player's unplaced pieces. The player with the fewest remaining squares wins.

Bonus scoring: If you place all 21 of your pieces, add 15 bonus points. If your last piece placed was the 1-square monomino, add an additional 5 bonus points (20 total bonus).

In competitive play, scores are often negative (pieces remaining minus bonus). The player with the highest score (least negative or most bonus) wins.

7 Strategy Guide

Expand Aggressively in the First Half

The board is large (400 squares for 4 players with 84 total pieces). Early game is about claiming territory and opening as many corner-touch points as possible. Players who expand slowly get boxed in. Use larger pieces first to establish a broad presence across the board.

Watch Your Corners

Every piece you place creates new corner-touch points you can build from later. When placing, favor pieces that leave open corners pointing toward open board territory rather than toward opponent pieces or edges. Your "reach" is determined by your available corners.

Block Opponents' Expansion Routes

Place pieces adjacent to opponents' pieces to limit their expansion corridors. If you can position yourself so an opponent has no room to grow toward the center, you win the spatial battle even if you haven't placed many pieces yet.

Save Small Pieces for Last

The monomino and domino are your most flexible pieces for filling tight spaces late game. Do not waste them early when large pieces can serve the same purpose. A 1-square hole at the end of the game can only be filled by the monomino.

Pentomino Priority

Your 12 pentominoes (5-square pieces) are the hardest to place and give the most territory. Try to place at least 8 to 10 of them per game. Saving them for late game is a common beginner mistake -- the board becomes too congested to use them by then.

8 Variants

2-Player Blokus

Each player controls two colors. Blue/Red for one player, Yellow/Green for the other. Players alternate turns with each of their colors (Blue, Yellow, Red, Green). The player whose two colors combined have the fewest remaining squares wins. Much more complex than 4-player.

Blokus Trigon

Played on a hexagonal grid with triangular pieces instead of square polyominoes. Same corner-touching rule but applied to a triangular grid. Creates a completely different spatial challenge.

Blokus 3D

3D version with cubic pieces placed on a 3D grid. Considerably more complex, for committed fans of the base game.

9 FAQ

Blokus Piece Reference: All 21 Shapes

Each player has 21 pieces in their color — one of each polyomino shape (1 to 5 squares). Here are the piece counts by size:

Scoring: How Unplayed Squares Are Counted

Maximum possible score per player: +20 points (all pieces placed, last piece is the 1-square). Minimum: −89 points (no pieces placed).

Advanced Strategy Tips

• Start aggressive — expand quickly. In the first few rounds, use large pentomino pieces to claim as much territory as possible. The player who controls the center early has more placement options later.
• Leave corner-touch opportunities. Plan pieces so their corners point into open space. Each piece needs to touch your own pieces corner-to-corner — think several moves ahead about which corners remain accessible.
• Block opponents' expansion paths. If you see an opponent heading toward an open corner of the board, intercept. A piece placed to deny their expansion is often more valuable than one that simply claims empty space.
• Save small pieces for late game. The 1-square and 2-square pieces are easiest to tuck into tight gaps late in the game. Don't waste them early when large pieces fit better.
• In 2-player Blokus Duo, the board is smaller (14×14) and play is far more tactical from move one. Block hard and fast.
• The X-pentomino is the trickiest piece. The X shape (plus sign) requires a completely isolated corner — plan for it early or you may never find a legal spot.

More Frequently Asked Questions