The aim of the game is to prevent the grid from overflowing by popping words. The maximum length of a word is 8 letters. Longer words score many more points than shorter words.
Play Popword by click and dragging across adjacent letters in the grid and releasing the mouse button when you have selected a word. Each successive selected letter must be directly next to the previously selected letter. If the word you have selected is a valid English word, the letters will 'pop' away and the letters above them will fall to take their place.