Keep the bad guys away from the Great Snow Tree by placing snowball launchers and other attack equipment along the bad guys' path. For every bad guy you stop, you'll get gold coins, which you can use to buy and upgrade equipment. To station attack equipment, click it in the toolbox. Blue squares will appear. Click the square you'd like to place the equipment in. When you're ready for the bad guys to approach, click Go, in the top-left corner, or wait until the countdown reaches 0.