In each level, the goal is to remove all the squares from the field. In each move, you have to remove the given number (n) of squares at once. The squares removed in one move must all be in the same row or column, they might have empty spaces in between, but you can't skip any blocks. To remove the squares you first select one block by touching it (it will turn dark green). The system will than highlight (in lighter green) the n blocks in each direction that could be removed - select the direction by touching one of the highlighted blocks (or touch the selected one again to unselect). It starts out with just 2 blocks to remove at the time, but that number will increase while you progress through the 50 level. The first levels are pretty easy but it will get harder over time.