Gangsters, mobsters, thugs, and all sorts of other shady figures are going to attack you, coming towards you from various directions, but they are not prepared for you to be able to shoot ice at them and freeze them up, which is what you are attempting in this game, using the mouse to slide in the direction you want to shoot ice.
After they are frozen up you will activate the second hand, with which you shoot fire blasts at them in order to destroy the block of ice they have become, and get rid of all your enemies to clear a level, with their numbers increasing level by level.
You also need to be careful of the ones that will shoot cannons or other weapons at you, since they need to be dealt with before they can inflict damage on you too much!