even better, once you get to the harder levels, hole up in the small room in the upper right hand corner. use the turrets to take out guys coming in through the bottom while you repair the 3 walls and kill the guys who stack up behind them
this game is awful possibly the worst game on kongregate. Use pixel level collision detection rather then being lazy and using the built in collision detection. It is absolutely infuriating to lose when you know full well your dog was not hit.