Type each of the words as they falls down. If you type a word correctly it will disappear. If you make a mistake you'll hear a "boing" sound and the word you're typing will be cancelled, so you'll have to type it again. You can type the words in any order. The objective, however, is to clear all the words before they hit the ground. If a word hits the ground you'll hear an explosion and will lose one life. (That's the green hearts at the top of the screen.) Lose all five lives and you'll have to repeat the level. Otherwise you'll move on to the next level. There are 34 levels in all.
You can jump to any level using the dropdown list box
You can control the speed of the game using the slider. Move it to the left to slow down the descent of the words; move it to the right and things will speed up. The game will also speed up if it appears too easy for your typing speed.
If you change the speed, the level will restart. You can also press "Enter" at any time to restart a level.
Note: The dropdown box to change level does not appear to work consistently in Opera.
Note: In Chrome there are some "trails" created by above tone marks. This appears to be a bug in Chrome. However, it shouldn't affect the game's playability.