Missile Commander, as you would have guessed, is a clone of the old Atari classic, Missile Command. Your goal is to protect Earth from an onslaught of incoming missiles by shooting them down with missiles of your own. The game continues indefinitely until you are inevitably destroyed by the ever increasing numbers projectiles.
Fans of the original game may be thrown off by a few of the gameplay changes. For one, your missiles no longer explode where you click, meaning you can no longer rely on the blast radii of your projectiles to knock out large groups, instead you must intercept the missiles with pinpoint accuracy and rely on the missile's own explosion to destroy others around it. You are also limited to one projectile on screen at any time and there are no specific cities to protect.
Don't be put off by these changes; Missile Commander is a genuinely addictive arcade game. You are guaranteed to distract coworkers, neighbors, and family members as you shout obscenities at your own inability to aim, yet continually click the retry button.
Missile Commander does not get a perfect 10, however, because it fails to bring anything new to the table. I've seen the previously mentioned alterations in other clones, so I can't really call it innovative. I would have liked to have seen power-ups, such as the ability to shoot more rockets or place shields. While I was drawn back to playing it several times again, the experience was predictable. Power-ups could have improved that.
Overall, Missile Commander does an excellent job of recreating the addicting qualities of the original. A few things could be changed, but you should definitely give it a shot.