5 Quadrat is a collection of 25 puzzles for one person and games for two or three players, all played on a 5x5 grid with various pieces (wooden discs in several colors, matches, and dice). Most of the games are traditional games played on such a board or traditional games adapted to the board. Credit is given in the rulebook to the books that they got the games from. Four of the games are original. One other, Harlekin, is by Hajo Bücken; the rules say it was originally published in his Arbeitsstelle für neues Spielen but it is not clear what it was called there.