Canyon is a good thing, especially if the canyon such as you, or zigzag, or spiral-like. In general, it is good to build him his protection. Place the gun in the most convenient locations, so that with his position and angle they could hit the widest possible field and their projectiles reached enemies everywhere. Develop your towers, earn money and build a new, more powerful and more durable tower to serve as a tomb for your enemies. Show someone else how do you know how to fight well let them never never want to come back to you. Forward!