Tanks But No Tanks

As the lone defender of the last remaining outpost, you are under attack by an overwhelming force of mysterious phantom tanks that disappear and reappear at will while destroying all that stands in their way. Your vital mission is no simple task--defend the outpost and destroy the enemy as they advance relentlessly through your defense mazes. Only brilliant strategy, perfectly executed can save you--and the free world.

You start out with five tanks in each of the four variations. There are three different screens, each one harder than the last. In the first screen, you have many walls and corners to hide behind. In the second, you have only a small island to protect your base, and in the third it's just you against them.

n each screen you must defend yourself against 20 enemy tanks. Since they're not all on the screen at the same time, there's an indicator right under your base telling you the enemy's remaining strength.
Also, at the beginning of each game, or after one of your tanks is destroyed, or at the beginning of each scenario, the number of tanks you have left is displayed where your tank begins.