It's a simple game to play -- It's sort of a tile based matching game, where you need to spot 3 or more of the same color tile, then click them to remove. The only problem is that while you're looking for them, there are more tiles being pumped into the playing field from the top *AND* bottom.
Your basic goal is to ensure there's enough room in the playing field so that the thing doesn't explode when the next sets of tiles are shoved in. (In other words, in each column there needs to be at least two blank spaces, so the tiles can be shoved inwards without impacting on each other).
As the levels go up, the amount of time between new tiles is shortened, you'll need to deal with more rows, and more colors are added at levels 10 and 20.