Each stage starts with a few asteroids drifting in random directions on the screen. Objects wrap around screen edges — for instance, an asteroid that drifts off the top edge of the screen reappears at the bottom and continues moving in the same direction. As the player shoots asteroids, they break into smaller asteroids that frequently move faster and are more difficult to hit. Smaller asteroids also score higher points. Periodically, a flying saucer appears on one side of the screen and moves across to the other before disappearing again. The saucers are of two kinds: Large saucers fire in random directions, while small saucers aim at the player's ship.
The minimalist soundtrack features a memorable deep-toned electronic "heartbeat", which quickens as the asteroid density is reduced by the player's fire.
Once the screen has been cleared of all asteroids and flying saucers, a new set of large asteroids appears. The number of asteroids increases each round up to a maximum of twelve. The game is over when the player has lost all of his/her lives.
Like many games of its time, Asteroids contains several bugs that were mostly the result of the original programmers underestimating the game's popularity or the skill of its players. The maximum possible score in this game is 99,990 points, after which it "rolls over" back to zero. Also, an oversight in the small saucer's programming gave rise to a popular strategy known as "lurking" — because the saucer could only shoot directly at the player's position on the screen, the player could "hide" at the opposite end of the screen and shoot across the screen boundary, while remaining relatively safe. This led to experienced players being able to play indefinitely on a single credit. This oversight was addressed in the game's sequel, Asteroids Deluxe, and led to significant changes in the way game developers designed and tested their games in the future.
On some early versions of the game, it was also possible to hide the ship in the score area indefinitely without being hit by asteroids.
The original design concepts of the DVG came out of Atari's off-campus research lab in Grass Valley, CA, in 1978. The prototype was given to engineer Howard Delman, who refined it, produced it, and then added additional features for Atari's first vector game, Lunar Lander. When it was decided that Asteroids would be a vector game as well, Delman modified a Lunar Lander circuit board for Ed Logg. More memory was added, as was the circuitry for the many sounds in the game. That original Asteroids prototype board still exists, and is currently in Delman's personal collection.
For each picture frame, the 6502 writes graphics commands for the DVG into a defined area of RAM (the vector RAM), and then asks the DVG to draw the corresponding vector image on the screen. The DVG reads the commands and generates appropriate signals for the vector monitor. There are DVG commands for positioning the cathode ray, for drawing a line to a specified destination, calling a subroutine with further commands, and so on.
Asteroids also features various sound effects, each of which is implemented by its own circuitry. There are seven distinct audio circuits, designed by Howard Delman. The CPU activates these audio circuits (and other hardware components) by writing to special memory addresses (memory mapped ports). The inputs from the player's controls (buttons) are also mapped into the CPU address space
The main Asteroids game program uses only 6 KB of ROM code. Another 2 KB of vector ROM contains the descriptions of the main graphical elements (rocks, saucer, player's ship, explosion pictures, letters, and digits) in the form of DVG commands.
The Killer List of Videogames (KLOV) credits this game as one of the "Top 100 Videogames." Readers of the KLOV credit it as the seventh most popular game.
The gameplay in Asteroids was imitated by many games that followed. For example, one of the objects of Sinistar is to shoot asteroids in order to get them to release resources which the player needs to collect.
Asteroids has been ported to multiple systems, including many of Atari's systems (Atari 2600, 7800, Atari Lynx) and many others. The 2600 port was the first game to utilize a bank-switched cartridge, doubling available ROM space. A port was in development for the 5200 and advertised as a launch title but never officially released, although an unofficial release was produced by AtariAge. 1993 saw a release for PCs with Windows 3.1 as part of the original Microsoft Arcade package. Also, a new version of Asteroids was developed for PlayStation, Nintendo 64, Windows, and the Game Boy Color in the late 1990s. A port was also included on Atari's Cosmos system, but the system never saw release. Many of the recent TV Games series of old Atari games have included either the 2600 or arcade versions of Asteroids. Atari has also used the game for its other late '90s and 2000's anthology series. Essentially, if one looks for this game, one will be able to find it somewhere.
In 2004, Asteroids (Including both the Atari 2600 port and the arcade original, along with Asteroids Deluxe) were included as part of Atari Anthology for both Xbox and Playstation 2, using Digital Eclipse's emulation technology. (This package was released for the PC a year earlier under the title Atari: 80 Classic Games in One.)
Glu Mobile released a licensed cellular phone version of Asteroids that includes the original game as well as updated gameplay, skins, and modes.
Also, a port for Rockbox was released, named "Spacerocks".
There have been countless unofficial ports of Asteroids produced. These include near-copies such as Acornsoft's Meteors and Ambrosia Software's Maelstrom, as well as those with expanded gameplay and background, such as Astrogeddon, Stardust, Spheres of Chaos and Astro Fire. The Vectrex had a built-in similar game called "Minestorm".
On November 13, 1982, 15-year-old Scott Safran of Cherry Hill, NJ, set a world record of 41,336,440 points on the classic arcade game Asteroids. He beat the 40,101,910-point score set by Leo Daniels of Carolina Beach on February 6, 1982. To congratulate Safran on his accomplishment, the Twin Galaxies Intergalactic Scoreboard searched for him for more than fifteen years, until 2002, when it was discovered that he had died in an accident in 1989. In a ceremony in Philadelphia on April 27, 2002, Walter Day of Twin Galaxies presented an award to the surviving members of Safran's family, commemorating the Asteroid Champion's achievement.
In March 2004, Portland, Oregon resident Bill Carlton attempted to break the world record for playing an arcade version of Asteroids, playing over 27 hours before his machine malfunctioned, ending his record run. He scored 12.7 million points, putting him in 5th place in the all-time Asteroids rankings.