Each round in Tapple, one player draws a topic card, then starts the timer. In the next ten seconds, that player must give a single word answer that fits within the topic, press down the letter key in a special electronic device that corresponds to the first letter of that word, and restart the timer. The next player must then think of a word for the topic that starts with a different letter, press down that starting letter, and restart the timer.
If a player runs out of time, they're out for the round. If only one player remains in a round, they collect the topic card. If players manage to press down all of the letters before knocking all but one player out of a round, the players reset the device, draw a new topic card, then start the timer again, this time needing to give two answers for the topic – each starting with a different letter — within the allotted time. Whoever collects the most topic cards wins!
