When the game begins, get all the requirements for the Recycler Building. Buy as many recycler buildings as possible, but do not exceed more than five of them or it will be difficult to have room for other objects.
-During the early levels, place a few towers near the entry point and at least one tower about a third of the way on the map to kill enemies that evade the first towers.
-Flying enemy aircraft appear at about the seventh attack wave, so have an anti-air gun somewhere in the middle of map. Do this by clicking the "Advanced" tab, then select the AA Gun for $150.
-With enough money, purchase a Wall Factory. The wall part will appear. If you want more walls to place quickly, instead of waiting for it to load, set the wall where desired then sell the Wall Factory. Purchase it again and put it back in the same location. The wall thing will show up as loaded. Do this repeatedly to place as many walls as possible.
-Once there are enough objects on the screen, you can stack buildings, making the game very easy.
-When you can build the Recycler, just stack as many of those as possible while maintaining defenses. The amount of money you are making will increase significantlyy. Once you can build the armor piercing guns and the chaingun, a few stacks of about ten or twenty of them will suffice. You can then focus on building lots of Recyclers for the score increases.
W hen your place is all covered and you have unlocked the Goo Cannon, put the Goo Cannon in one side. In other side put as many as desired. You will slow down their enemies and take down their health quickly.