Illuminations is an action game centered around fireworks. The goal is to shoot the rising rockets in order to set them off. Do a good job and you'll create a spectacular show of light. Miss too many rockets, and it's game over.
Enemies will spawn to slow down your attempts. Shoot them as well to add to the show, and to prevent them from stopping you. Each rocket you miss will lower the crowd excitement meter, as will each stun shot you receive from enemies. Hitting rockets will raise the meter. If the meter reaches zero, it's game over.