For this game you don't need to click the Fuzzy Monsters; just hover over them with the mouse. After four monsters, the screen will flash indicating you've moved to the next level, where the monsters are smaller and faster. The game lasts until you miss three monsters in a row.
The monster is a puppet I use on my YouTube channel. I got the idea for this game from watching my daughter play one of those "Whack-a-Mole" style games at an arcade.