A sequel later appears in Citrus Tower under the title Shoot-'em-up 2.
This game is played in first person view from the spaceship. A varying number of aliens will appear on the screen one by one in groups. All aliens have appeared when the music reaches the end of its chorus. The player must then repeat the number and time they appeared, relying on the rhythm of the music. If a beat is missed, that alien will escape and damage your spaceship. Pressing A or D-Pad will shoot and destroy an alien. Notice that there are only two waves of aliens coming in two verses in this game instead of three.
A or D-Pad: Shoot
Simple Tap Mode
Hit: The alien is destroyed completely
Barely: The alien is only disabled, not completely destroyed. A barely counts as a miss.