Blokus Solitaire

Blokus Solitaire is a single-player adaptation of the popular board game Blokus. The player must place polyomino pieces of increasing size onto a grid, following one crucial rule: each new piece must touch at least one of the player's previously placed pieces, but only at a corner — never along an edge. The goal is to place as many pieces as possible (ideally all 21 pieces of one color set). The corner-only contact rule creates a distinctive branching pattern that grows outward across the board.

Rules

1. You have a set of 21 polyomino pieces: one of each shape from 1 to 5 squares (1 monomino, 1 domino, 2 trominoes, 5 tetrominoes, 12 pentominoes).
2. The first piece must be placed touching a corner of the board.
3. Each subsequent piece must touch at least one of your previously placed pieces at a corner (diagonally adjacent).
4. No piece may share an edge (side-by-side) with any of your previously placed pieces.
5. Pieces may be rotated and flipped freely.
6. The goal is to place all 21 pieces. If you get stuck, try to maximize the number of pieces placed and minimize the total area of unplaced pieces.

Strategies

• Start from the Corner: Place your first piece in a board corner to maximize outward expansion.
• Expand Diagonally: The corner-only contact rule naturally pushes growth diagonally. Spread toward the center of the board as quickly as possible.
• Place Large Pieces Early: The pentominoes (5-square pieces) are the hardest to place later when space is restricted. Use them early while the board is open.
• Maximize Contact Points: Each piece you place creates new corner contact points for future pieces. Choose placements that create the most new corners, particularly corners that point toward open board space.
• Avoid Blocking Yourself: When placing a piece, check that it does not share an edge with your other pieces — this is the most common mistake — and that it does not cut off access to large open areas.
• Save Small Pieces for Last: The monomino and domino can fit into tight spaces. Save them for endgame when the board is crowded.

Blokus was invented by Bernard Tavitian, a French mathematician and game designer, who patented the game in 2000. Tavitian, who was born in 1942 in Lebanon and later moved to France, spent several years developing the game. He reportedly came up with the concept while researching mathematical polyomino tiling and looking for a way to turn it into a competitive multiplayer game.

The game was first published by Sekkoïa in France in 2000, and its international rights were quickly acquired by larger publishers. Mattel obtained the global rights in 2009 and continued to produce and market the game worldwide. Blokus won numerous awards, including the Mensa Select award in 2003 and the Teachers' Choice Award, establishing it as both an entertaining game and an educational tool.

The original Blokus is a multiplayer game (2-4 players), where each player has their own color set of 21 pieces and competes for board space. The solitaire version strips away the competitive element and focuses on the spatial puzzle: can you place all 21 pieces while obeying the corner-only contact rule? This version became popular among solo puzzle enthusiasts and was formalized in apps and digital versions.

The game's connection to polyomino mathematics gives it depth beyond typical board games. The 21 pieces represent all free polyominoes from size 1 to 5 (1+1+2+5+12=21), covering a total of 89 unit squares. The corner-contact rule creates emergent complexity: simple to understand, but the branching possibilities grow exponentially with each piece placed. Blokus has been used in academic research on computational complexity and has been shown to be NP-hard in its general form. The game remains widely popular in schools, game clubs, and households around the world.