Li-Nuggz is a modern remake of the early 80s classic Cannon Ball / Bubble Buster, which was also remade in the late 80s as Pang. In case you're unfamiliar with any of these titles, the idea is to shoot bouncing bubbles to make them smaller and smaller until they disappear. You mustn't touch them though.
The levels in Li-Nuggz have been arranged into a Super Mario-style island where you progress from one screen to the next but can revisit any previous level at any time. There are also several mini-games that can be accessed from the main menu, which are variations on the main gameplay style. This provides a good variety of gameplay based around a fairly simple idea.