GROWL is a psychedelic arcade game made in 48 hours for Ludum Dare, a game development event. It focuses on hard gameplay and visual experimentations.
Rotate your laser by tapping on the sides of the screen, and line up the red rectangle with the end of each note. The note you currently need to complete is displayed in green.
A help button is available at the upper-right corner of the screen. The other circle-shaped button lets you switch between "normal" and "pixellated" draw modes.
You can also check out the gameplay video before playing, so that you know how the game works.