A list of words on one theme is hidden in the block of letters; each one sits in a straight line — across, down or diagonally — and appears exactly once. In the gentler puzzles every word reads forwards: left to right, top to bottom, or diagonally downwards. From difficulty 3 upwards, words may also read backwards or upwards. With a mouse, drag from a word’s first letter to its last; on a touchscreen, tap the first letter and then the last.