@rbertolucci: upgrade your towers at least 40 times. Use the "+30 waves" option, build enough towers and update them often enough that the sum of all upgrades is at least 40.
@Orgy: Use the "+30 waves", "double health" and "double enemies per wave" option. You will have to deal more than 250000 in order to win.
 "Hands of War Tower Defense"){kind=icon}