Alien Warnings

Aliens give off a warning before carrying out certain actions.

Glowing Green

This means an alien is about to bring up a shield, and dive-bomb vertically down to the bottom of the screen. Make sure you are not underneath the alien when it does this.

Purple Pulse

- This means the alien will explode into one or more firebombs when hit.

Purple Pulse turning Red

- This means the alien is about to bring up a shield, and move down the screen in a diagonal trajectory.