If you put all cannons you can literally go until the game stops getting harder and then its just a question of do you want the high score or do you want to suicide yourself and quit playing. If the best strategy is to use only 1 type of turret the game needs tweaks. The fire should be able to go thru enemies and damage the one behind. The difficulty should continue to escalate. After the first 15000 points nobody could touch my shack until I chose to lead them to it and suicide.
iGleepGlop about Zombie Attack!