In this version of Asteroids you pilot an asteroid and must avoid a field of starships that fire at you. When your asteroid is hit, it shrinks in size.

From Wikipedia, re: Asteroids:

Asteroids was inspired, in a roundabout way, by the seminal Spacewar!, the first computer-based video game. In the early 1980s a stand-up arcade game version was produced as Space Wars, which included a number of optional versions and added a floating asteroid as a visual device. Asteroids is essentially a one-player version of Spacewar!, featuring the “wedge” ship from the original and promoting the asteroids to be the main opponent.

The game was conceived by Lyle Rains and programmed and designed by Ed Logg. Asteroids was a hit in the United States and became Atari’s best selling game of all time. Atari had been in the process of releasing another vector beam game, Lunar Lander, but demand for Asteroids was so high they stopped further production of Lunar Lander so they could begin building Asteroids. The first 200 Asteroids machines were sent out in Lunar Lander cabinets. Asteroids was so popular that video arcade owners usually had to install larger boxes to hold all the coins this machine raked in.

One feature of the game was the ability for players to record their initials with their high scores, an innovation which is standard in arcade games to this day.