Place 'towers' (coloured gems that can shoot bullets) on strategical spots to defend the storage from monsters! You can use special powers: lightning, hypnosis and 'towers boost'. The first does a lot of damage, the second hypnotizes the monsters for a second and the last makes your towers faster and stronger. You can find these special powers in the down-right corner of the screen. When you click on the save point, you can buy extra lives. You need to have earned enough coins first, of course!
Click three times on a spot to place a gem on the road. When you built all towers, click on the feet or press Space to let the wave start.