Lexiboard

Goal

Build words on the board by crossing the ones already played, as in a crossword grid, and score more points than your opponents.

How it works

• Each player gets 7 letters drawn from a bag of 100 tiles, including 2 blanks.
• The first word, of at least two letters, must cover the centre star.
• The letters played in a turn form a single row or a single column, with no gap, and connect to the existing words.
• Every word formed must be in the dictionary (more than 260,000 words).
• You can also exchange letters, if at least 7 tiles remain in the bag, or pass your turn.
• After each move, the rack is refilled to 7 letters.

Scoring

• Each letter is worth 1 to 10 points; the blank is worth 0.
• The letter ×2 and letter ×3 squares multiply the tile placed on them; the word ×2 (including the star) and word ×3 squares multiply the whole word.
• A premium only counts on the turn its square is covered.
• Playing all 7 of your letters at once is a bingo: a 50-point bonus.

End of the game

The game ends when a player plays their last tile while the bag is empty: they add the value of their opponents’ remaining letters to their score, and the opponents subtract it from theirs. It also stops after two full rounds with no word played; everyone then subtracts their remaining letters.

Controls

• Drag a letter from the rack to a square, or tap a letter then a square.
• On the keyboard: click a square, then type your letters (Space changes direction, Backspace erases, Enter submits, Esc takes everything back).
• Tap a placed letter to take it back; drag the letters of the rack to reorder them.

About the AI

The AI generates every legal move with the Appel and Jacobson algorithm (anchor squares, cross-checks, a prefix tree of the roughly 270,000 words of the dictionary, built in a separate thread). Master level plays the move with the highest equity (points scored + value of the leave on its rack), avoids opening the triple word squares, exchanges wisely and calculates the endgame from the letters that remain, as a player who counts tiles would. Lower levels stick to everyday vocabulary and deliberately choose lower-scoring plays.