Click an attack. When you click it, while the audio cue plays, press "Now!" to do extra damage. Each attack has a recharge amount. Look at the cooldown to know when your cooldown is over. Your enemy also has a cooldown, but the number is invisible.
This was built off of "Turtleman", which was one of my projects created as a request from one of my classmates. "Eem: The Battle" adds buttons, timed attacks, new audio, better visuals, and stingrays!