Crazy Snakes

In Mexico, began the invasion of the snakes. Why is that environmentalists do not know. But you need to get rid of them in any way, otherwise they would flood the entire planet! Your job is to stand bravely at the border about guns, customize them, to clarify the flight speed of the nucleus and shoot at each of nasty snakes, which spoiled you and your friends life! Be precise and labels, and the rest will come!