The enemy in an interplanetary war has gone underground, and you're piloting the ship that's taking the fight to him. But he hasn't just hidden away in a hole; he's hidden away in a very well-defended hole. As if it wasn't already going to be enough of a tight squeeze navigating subterranean caverns on Mars, you're now sharing that space with enemy ships and any number of other fatal obstacles.

(Fortunately, the enemy also leaves copious numbers of helpful fuel depots for you too.) Once you fight your way to the bottom of the cave, you plant charges on the enemy mothership - meaning that now you have to escape the caverns again, and fast. (Atari, 1981)

Atari wisely realized that some of the best programming talent wasn't necessarily on its own payroll. With so much of the company's financial resources devoted to supporting the 2600, this paved the way for the Atari Program Exchange, a program that allowed users to send in their own best work to Atari, who would then list the best of these homebrew games and applications in an official newsletter and handle distribution on cassette and floppy disk.

Provisions were built into the APX structure for royalties to the original programmers, and it quickly became clear that Greg Christensen, the designer of Caverns Of Mars, had come up with a winner. So much so that Atari later negotiated with him for the rights to release a cartridge version; as popular as Caverns Of Mars was as an APX release, that really just represented the die-hard segment of the Atari user base. The cartridge broke Caverns into the mainstream, and inspired quite a few imitators on other platforms (such as Cavern Creatures on the Apple II, to name just one example).

Rating:  A whole dollar - trade it in for more quarters, you'll be playing this one a lot.