Enemies want to kill you. But, you can't let that happen. You have to shoot them before they shoot you. Also, there are various explosives throughout the different levels that you can shoot to blow up a bunch of enemies. There are also health kits that you need to click on to replenish your health. This isn't just a 'shoot'em'up' kind of game - you actually have to interact with people, and you will need to pick up different objects to get you through to other levels. Everything is done with the mouse. Use the mouse to aim, and use the mouse button to shoot or pick stuff up.