hint for survival, before you go in have at least unlimited ammo (it helps to have all of the upgrades) then get the tesla gun (it shouldnt take long before a bat drops one) the just put your mouse in the centre of the mushrooms and put cello tape on your mouse, then you can just go off and do something else, the highest level i got to was 100 but that was just because i wanted to go on the computer. you could probably go on for a much longer time but i dont know just yet
 "Caribbean Admiral"){kind=icon}
 "Mushroom Madness 3"){kind=icon}