Guggenheim is a paper-and-pencil parlor game for two or more players, but it can also be played solo. It was the basis for the commercial games Scattergories and Facts in Five.
Each player draws a 5×5 grid on a sheet of paper, leaving the cells wide enough to write words inside them. (Alternatively, players may use copies of the grid here: https://www.gamerulesguru.com/pdfs/guggenheim.pdf) The players then agree on five categories (countries, cars, actors, etc.) and write one category to the left of each row. One player selects a five-letter word at random, with no repeated letters, and the five letters of that word are written above the grid, one letter per column.
The players agree on a time limit, such as two minutes, and one player seta a timer for that amount. Once the timer starts, players try to fill in the cells of their grids with words. Each word must fit the corresponding category and begin with the corresponding letter.
Suppose the key word is WAGON, and one of the five categories is "animals". Valid answers might be walrus, aardvark, giraffe, otter and newt.
Score the most points by filling in more boxes than any other player, or by having the greatest number of unique answers. The player with the highest score wins.
A player scores one point for each word in his grid. A unique answer (one not given by any other player) scores two points.
The time limit can be varied, as can the number of categories and the length of the key word (the latter two need not be equal). One common variant is to allow players to write more than one answer in a cell, for a better chance at a winning score. Another variation is to allow players to score only for unique answers, crossing off or disregarding answers shared with another player.