This is quite a classic of puzzle games. I personally love this one so I wanted to have one of my own design created for Android.
Gems of different colors pop up and you can slide them. If you put a row of five or more gems of the same color (horizontal, vertical, diagonal) they disappear and you score points. If the board is full the game is over. Gray gems (on level 1 only) act as 'jokers' and substitute any color.
You can undo last move. You can also select one of five gem sets.