Galaga was an old arcade game released by Namco way back in 1981 (it was licensed to Midway in America).
The story
Galaga was the sequel to Galaxian (a great game in its own right), and quickly became one of the most popular video games ever made. This title first made its debut in the arcades, but was quickly ported to the Atari 2600, Atari 5200, Atari 7800, Atari 400/800, Nintendo Entertainment System, Colecovision, and nearly every other console on the market. This is the most successful shooter title ever released, and was followed up by four arcade sequels Gaplus, Galaga '88, Galaxian3, and Attack Of The Zolgear.
Galaga was also one of the most bootlegged titles around. It is estimated that there were more bootleg copies of this game made than there were actual licensed versions. Although not nearly as many of the bootlegs have survived to present day, as their boardsets were generally of inferior quality, and were not documented, making them hard to repair.
The game
You have probably already played this game at some point in your life (if you haven't, then you probably never play games at all). The general formula is one that has been used for countless games. You control a spaceship that can move left and right along the bottom of the screen, and you fire at rows of enemies at the top of the screen.
The bug like enemies will fire at you from above while moving back and forth. Individual ships (and groups of ships), will break away from the armada to make attack runs at your fighter. Most of the ships are killed with a single shot (although the "Galagas" or motherships take two hits to kill). The "Galagas" (motherships), will attack with two escort ships, and may try to pull your ship in with a tractor beam. If you allow this, then your ship will go up to the formation with the mothership. You can then shoot the mothership down on its next attack run, this will earn you "double ships" which gives you two attack ships side by side.
Once every few levels you will get a "Challenging Stage" where ships will fly by in patterns, and you get to shoot at them with no fear of attack. There will always be 40 ships total, and hitting all 40 of them will get you the highest score (it is easy with a bit of practice).
There are several well known bugs in this game, but the only one really worth reading about is the infamous "No shoot" bug (which doesn't work on the new Galaga/Ms. Pac-Man machines, but works fine on the original, and most bootlegs). Here is how it works. Start a new game and kill everything on the first level except the two bees in the bottom left corner. Then you have to dodge their shots for about 15 minutes (until they stop shooting). Then let them pass 5 more time before you finally kill them. The enemies will not fire at you for the rest of the game. (Either player can do this in two player mode, and it will affect both people).
If you are going for a record score, then be aware that you are going to want to play as the second player (start a 2 player game, but just let player one die). For some reason the player one score rolls over at a million points, while the player two score rolls over at 10 million points. If you are that good, then you will probably encounter a few other of Galaga's limitations. The first is that the game only has 255 levels, and will crash after the final level is finished (just kill yourself off at 255, so your high score will be displayed, and you can see your stats). Finally no new extra men are earned after 1,000,000 points (although you probably won't need them if you can make it that far).
The Machine
Galaga machines came in four formats (not counting bootlegs, which were all different).
Upright machines were the most common, and accounted for the vast majority of all Galaga machines. They were in cabinets that were identical to the Pac-Man/Galaxian design, and most of them were black (although a few white ones were made as well, perhaps they ran out of black paint, or filled up a few left over Galaxian cabinets). The sideart consisted of a large oval shaped sticker with an image of one of the buglike enemy ships (these stickers are reproduced by several companies, and Namco still has some in stock that are left over from the new Ms. Pac-Man/Galaga - Class Of 1981 machine). Two different marquees exist. The common one is a green "Galaga" logo on a black background, while the alternate one is a (totally different) gold "Galaga" logo on a white background. The control panel features blue graphics and a single 2-Way joystick, a fire button, and start buttons. Most machines also have a large sticker on the kickplate (front panel), that is another picture of the same bug ship that adorns the side of the machine (this sticker is also available as a repro, but Namco doesn't have any more originals left).
The mini cabinet is much smaller copy of the basic upright design (about a foot shorter, a foot shallower, and 6 inches narrower). These are finished in woodgrain and black, and seldom have any sideart. The marquee and control panel graphics match those of the upright.
The cocktail cabinet is a standard woodgrain Namco cocktail with a small control panel on each end, and some subtle "Galaga" labels underneath the glass (most cocktail tables look very similar to one another, and this one is no exception). These are generally the most valuable of all the Galaga machines (mainly due to the fact that they don't require a truck to haul, and look smaller in the eyes of the significant other, even though they technically eat a lot more floor space, as they need chairs on both ends.
Namco also produced a "portable" in very limited numbers. These used smaller screens and were similar in appearance to the little pay televisions that you might encounter in a bus station. They were designed for use on buses and airplanes, although very few of them ever saw service in that way.
Where to play
Galaga is one of the easiest titles around to locate. It has been ported to almost every console ever made, and several clones exist for nearly every operating system out there. Real machines are still in abundance out in the wild (the new Ms. Pac-Man/Galaga - Class Of 1981 version is especially easy to find). You are not going to have much trouble finding a copy of Galaga to play (unless you live in the Amazon Rainforest or something, even then, the nearest town will probably have an old bootleg copy somewhere).
This is one of those games that everyone wants in their arcade game collection. Which leads to it being very overpriced (see the Ms. Pac-Man node for details). So if you really want a Galaga, then you must ask yourself if you are willing to fork out a large chuck of change for this game, and if you are willing, then I have one suggestion for you. Don't buy an original 1981 Galaga, Instead buy the new Ms. Pac-Man/Galaga - Class Of 1981 machine. If you are going to spend a large amount of money on a game, then you might as well buy a brand new one that can give you many years of service (as opposed to a 20 year old one, that will undoubtedly need repairs down the road). If the $2000 price tag of one of these new machines scares you (and it will, trust me), just think about what a restored Galaga will cost you (around $1200 USD as of Feb 2002), then think about that $200 PCB repair it will need in a few years, then factor in that $300 monitor replacement that it will eventually need, and don't forget about the old style power supply, that will eventually fail). By the time you factor in those repairs, you are almost at that price for a new machine. Now consider the fact that you get Pac-Man and Ms. Pac-Man as well. You also shouldn't forget that this new title is JAMMA compatible, so you can buy other gameboards for it (your choices are very limited by the 4-Way joystick and vertical monitor, but there are still about 30 other JAMMA games that use that configuration). So you really might as well buy a new one (unless of course you run across a nice original Galaga for only a few hundred dollars).
If you do buy an original Galaga, then you may want to invest in a "fast shoot" chip. They are available from several vendors for about $20, and are quite easy to install (these may not work if you have a bootleg copy, so be warned).