The mechanics are very simple, right in front of your food (which could be a cake, a pizza or a pie) you have a gray zone where you can kill the ants. That is, although you see the ants coming from the beginning of the screen, you can only squash them when they get to the gray zone.
Thus, for each ant that you kill, you will get points, which afterwards will be compared with other scores from all over the world and will tell you how well you have done. It's a simple games without pretension.
Ant Smasher Free Game Best Fun is a very simple title that will entertain you for a few minutes, but not much more.