The object in Space Invaders is simple. Aliens are about to invade your planet, and you have to blast them before they can land. You have a blaster and three lives to shoot them down as they slowly advance downward one at a time, while also shooting at you. As the invaders thin out, they start moving faster. Occasionally, a UFO flies by that you can hit for bonus points. You also have three shields in the air to protect you, but as they take fire, they slowly erode. The game has an infinite number of levels, and ends if either you lose all three lives or if the Invaders reach the surface.
What's amazing about 2600 Space Invaders is the various options. While most other games at the time had 5 or 10 options, or even 30, this game has 112(!) variations to choose from. They include moving shields, guided shots, invisible invaders, two-player options and more.
The graphics are simplistic, but each row of aliens look different. The sounds are good, with some neat noises for the advancing aliens, plus a little sci-fi sound for the UFO.
You can't call yourself an Atari fan if you don't have this cartridge. It's a great game, featuring simplistic but fun gameplay, plus the massive options give it replay value you can't find very often.