Are you looking for a new game to fill your daily commute? Pebble Universe might just fit the bill. The physics-based puzzle game has made its way over to Android from iOS, and offers 25 levels of gameplay for free.
The storyline behind the game is quite straight forward: you're responsible for a group of Pebbles (naturally), who are being attacked by soot-lump creatures wanting to eat delicious Pebble meat.
Now, in order to protect themselves against the evil creatures above, the Pebbles take advantage of the fact that their hats explode when they bump into each other.