Number of Players
2 to as many as you like. Can also be played solitaire.
Paper and pencil
Each player draws a 5x5 grid on a piece of paper, leaving the boxes wide enough to write words inside of them. The players then agree upon 5 different categories (for example: countries, cars, celebrities, etc.), and fill them in along the left edge of their grid (1 category per row). A 5-letter word is then chosen at random (perhaps from a dictionary), and the 5 letters of that word are written along the top of the grid (1 letter per column).
A timer is set for an agreed upon amount of time (usually 2 minutes). Once the timer starts, players attempt to fill in all of the boxes of their grid with words. Each box must contain a word that fits the corresponding category, and starts with the corresponding letter. For example, if the 5 letter word is “wagon,” and one of the 5 categories is “animals,” then players must think of animals that begin with the letter w, the letter a, and so on (i.e. “walrus,” “alligator,” “giraffe,” “ostrich,” and “newt.”). Players continue writing until they have either filled in every box, or the time runs out.
Score the most points by filling in the most boxes, or coming up with the most unique words. The player with the highest point total wins.
Players score 1 point for each word on their grid, however, unique words (words that no other player has) are worth 2 points.
All manner of variations exist from the time limit, to the number of categories, to the length of the word (the number of categories and letters do not necessarily need to be equal). A common variation is to allow players to write more than one word in each category, thus providing them with a better chance of a high score. There is also a variation in the scoring, where players only earn points for unique words, and cross off or disregard any words they have in common with another player.