To summarize the game in one paragraph would be impossible, but basically the game consists of a space ship (the Defender) and aliens manning various types of spacecraft. They are intent upon not only destroying your ship, but also kidnapping the inhabitants of the city. Once kidnapped, the humanoids are changed into vicious mutants and return to earth to get you, and eradicate all vestiges of civilization. Since you alone are responsible for the protection of the city, your aim is to destroy the aliens and their ships, while at the same time protecting (and often rescuing) the hapless civilians from being captured.
Your Defender is equipped with missiles that are ussed to blast the alien ships. But, when things look bad (and trust us, they will), you can employ one of two last resort weapons. First, you have three smart bombs which blow up every alien in sight. With every 10,000 points you score, you earn another smart bomb and another Defender life. Use smart bombs sparingly and strategically. It is a good idea to keep one smart bomb in reserve to earn another Defender life. You can also hyperspace out of trouble, as in Atari's Asteroids. Of course, there's no telling where you'll reappear on the screen, so it should be used only when you've run out of smart bombs.
If it all sounds hectic, that's because it is. 5200 Defender will provide a substantial challenge to even the most seasoned space gamer. This is a fantastic translation. Tons of objects fill the sky, and with no flicker. The screen scrolls extremely smoothly. And the sound effects are second to none. It almost appears that Atari took the arcade game's sound samples and directly added them into the 5200 cartridge. Purists may scoff at having to play the game with a joystick, but novice Defender playes (that's about 99% of us) will actually find the joystick control much more intuitive, fluid and easier to master. And to me, at least, that's a good thing.