Idea: On next update (which will be when hell freezes :P) add an aim tool. If you click a weapon with the aim tool, it will make the gun stick to the mouse cursor, if you will click again, the gun will lock where you placed the gun, then, the gun will LOOK at the mouse, not follow it. When you click, it triggers the gun to fire where the mouse is.
guys i recommend you to download the android version of this game (or atleast it's a game that it called "the sandbox") it has much more materials and it also has some levels that you have to complete to unlock more materials
Rocket Launcher is coming in next week's update.