Similar to Centipede, the object of the game is to destroy a millipede that advances downward from the top of the screen. The millipede travels horizontally until it either hits an obstacle or reaches the edge of the screen, after which it drops one row and reverses direction. Once it enters the player’s gray maneuvering area, it stays there and extra heads appear at intervals until both they and the millipede are destroyed. Shooting a body segment splits the millipede in two, with the rear portion sprouting its own head. A collision with any enemy costs the player one life. New enemies and gameplay elements are introduced in Millipede: Earwig: same as the scorpion in Centipede, making mushrooms poisonous so that the millipede will charge straight to the bottom of the screen after touching them. Bee: same as the flea in Centipede, dropping mushrooms in a vertical line and requiring two shots to kill. Spider: same behavior as in Centipede, bouncing irregularly across the player area and eating mushrooms. Multiple spiders can appear at the same time on higher levels. Inchworm: when hit, slows all enemies for a short period of time. Beetle: crawls around the player area for a while, then climbs up and leaves the screen, turning any mushrooms it touches into indestructible flowers. When hit, everything on the screen scrolls down one row. Dragonfly: drops mushrooms while zigzagging down, and can be destroyed with a single shot. Mosquito: bounces off the sides of the screen as it descends diagonally. When hit, everything on the screen scrolls up one row. DDT bomb (stationary): can be blown up with one shot, destroying all enemies and mushrooms within the blast radius. Whenever the mushrooms scroll down, a new bomb is added at the top of the screen. Up to four bombs can be in play at one time. The player scores points for shooting the bomb itself, as well as increased values for any enemies destroyed in the blast. All flowers and poisoned/partially destroyed mushrooms revert to normal, whole mushrooms and score points during the process when the player loses a life. At regular intervals during the game, the player will face a swarm of enemies (bees, dragonflies, etc.) instead of the usual millipede. Each enemy destroyed awards increasing points, up to a maximum of 1,000 points per enemy; this attack ends when either the entire swarm has passed or the player loses a life. Also, at intervals new mushrooms will grow on the field while others die off, in a pattern similar to Conway’s Game of Life. Players can also choose at the start of the game whether to play at an advanced level, starting with a score that is a multiple of the number of points needed to earn an extra life (by default, 15,000). The gameplay is generally much more advanced than it would be had the player started with a score of 0 and worked their way up to that point level. The maximum advanced level allowed is a function of the preceding player’s score, and games started at an advanced level where the player did not earn at least one extra life are not eligible for the high scoreboard.

Missile Command is a 1980 arcade game by Atari, Inc. that was also licensed to Sega for European release. It is considered one of the most notable games from the Golden Age of Video Arcade Games. The plot of Missile Command is simple: the player’s six cities are being attacked by an endless hail of ballistic missiles, some of them even splitting like multiple independently targetable reentry vehicles (MIRVs), and in later levels smart bombs which can evade a less than perfectly targeted missile. As a regional commander of three anti-missile batteries, the player must defend six cities in their zone from being destroyed. The game is played by moving a crosshair across the sky background via a trackball and pressing one of three buttons to launch a counter-missile from the appropriate battery. Counter-missiles explode upon reaching the crosshair, leaving a fireball that persists for several seconds and destroys any enemy missiles that enter it. There are three batteries, each with ten missiles; a missile battery becomes useless when all its missiles are fired, or if the battery is destroyed by enemy fire. The missiles of the central battery fly to their targets at much greater speed; only these missiles can effectively kill a smart bomb at a distance. The game is staged as a series of levels of increasing difficulty; each level contains a set number of incoming enemy weapons. The weapons attack the six cities, as well as the missile batteries; being struck by an enemy weapon results in destruction of the city or missile battery. Enemy weapons are only able to destroy 3 cities during one level. A level ends if all the cities are destroyed, or when all enemy weaponry is destroyed or reaches its target. A player who runs out of missiles no longer has control over the remainder of the level. At the conclusion of a level, the player receives bonus points for any remaining cities or unused missiles. Between levels missile batteries are rebuilt and replenished; destroyed cities are rebuilt only at set point levels (usually 10 or 12K). The game inevitably ends when all six cities have been wiped out. Like most early arcade games, there is no way to “win” the game; the game just keeps going with ever faster and more prolific incoming missiles. The game, then, is just a contest in seeing how long the player can survive. On conclusion of the game, the screen displays “The End”, perhaps a poke at oncoming Nuclear Holocaust rather than the standard “Game Over” text (however, if the player is able to make the high score list, the game then prompts the player to enter his/her initials, with the “The End” sequence skipped). The game features an interesting bug: once a score of 810,000 is reached, a large number of cities are awarded (176 cities plus the continuing accrual of bonus cities) and it is possible to carry on playing for several hours. At some later stage the speed of missiles increases greatly for a few screens. On the 255th and 256th yellow screens, known as the 0x stages, the scoring increases by 256 times the base value. For good players these two 0x stages could earn over a million points. This enabled them to reach a score of approximately 2,800,000 (although only 6 digit scores were shown, so it would display 800,000) and at this point the accelerated rate would suddenly cease and the game would restart at its original (slow) speed and return to the first stage, but with the score and any saved cities retained. In this way it was possible to play this game for hours on end. Targeting crosshair: Aim your missiles quickly but carefully. Use the trackball to move the targeting crosshair to where you want the next missile to go, then press any Launch Control button to fire the missile. The missile will explode where the crosshair was positioned when the Launch Control button was pressed. Cities: There are six cities in total on the screen at one time, three on either side of the Delta Base. If one enemy missile or Smart Bomb manages to strike a city, that city will be wiped out. When all cities are destroyed, the game is over. Alpha Base: The missile base on the left side of the screen. Press the leftmost Launch Control button to launch an ABM from the Alpha Base. Delta Base: The missile base in the center of the screen. Press the middle Launch Control button to launch an ABM from the Delta Base. Omega Base: The missile base on the right side of the screen. Press the rightmost Launch Control button to launch an ABM from the Omega Base. NOTE: The Alpha and Omega Bases launch ABMs at a slower speed than the Delta Base, so you must plan further ahead when launching missiles from those bases. Defensive Missiles : The ABMs you launch to protect your cities. Each missile base contains 10 ABMs per wave. If any missile base is struck by an attack missile or smart bomb, the remaining stock of missiles for that wave are destroyed, and the missile base is rendered useless until the next wave. You receive bonus points for every ABM you have remaining at the end of each wave. Attack Missiles : Their only aim is to destroy your cities and missile bases. Every missile wave starts off with a hailstorm of attack missiles. They never deviate from their path. They may, however, turn into MIRVs. MIRV : Surprise! There is no warning when an attack missile turns into an MIRV (with multiple warheads). Think fast. Each new missile that the MIRV unleashes is carefully targeted. Killer Satellite: A mean-looking satellite that travels across the sky at a mid-level altitude and fires attack missiles. First appears in Wave 2. Bomber: A big slow-moving target that flies across the sky at a mid-level altitude, but watch out! It fires attack missiles. First appears in Wave 2. WARNING: If you destory a bomber or killer satellite before they deploy their missiles, you may see their missiles added to the downpour. An existing missile may also turn into an MIRV. Smart Bomb: Smart enough to avoid most explosion clouds from your ABMs. Your ABM must explode next to one in order to destroy it. You can also squeen it between two explosions to destroy it. First appears in Wave 5. ‘LOW’ Warning: As soon as there are only three ABMs left in a missile base, the game displays the word “LOW” underneath that base, and a warning signal sounds. Heed the warning.