Bubble Blast 2 for Android is a free puzzle game that, yet again, pits players against poppable, monochromatic bubbles. Choose from two game modes: Puzzle and Arcade.
In Bubble Blast 2, each level is covered in a different configuration of bubbles, with some bubbles being more difficult to pop than others. In order to advance, you must set off chain reactions of bubble-poppage to clear each screen. The game is not only fun and addictive, it's also quite a brain teaser, as it forces you to weigh several different courses of action when attempting to clear each level.
If you're looking for a challenging puzzle game to fill those sporadic free moments throughout your day, Bubble Blast 2 for Android is a great option. And since it has, literally, thousands of puzzle levels, it's almost guaranteed to wrack your brains for all of eternity. Or at least until Bubble Blast 3 comes out.