Just had a quick chat with the developers and they've offered some more detail:
- The game uses the PS Vita vertically only
- Touchscreen and/or rear touchpad can be used for moving the Sun
- Tapping Touchscreen/rear touchpad and/or L/R buttons can be used for shooting
- Shaking the device (using the accelerometer) is used to get rid of dead leaves on Autumn levels
- The camera is used to catch the ambient light during specific dusk tropical stages
Specifically a PS Vita release, it uses all the system's interfaces such as shaking and the touchscreen, and it plays with the screen held in portrait, which is a first, I think. With its bright visuals, tinkly tunes, if it was any jollier, it would explode in rainbows. Expect a release and a demo soon, with its classic, immediate style of hook, this looks like a winner.