Donkey Kong was an old arcade game released by Nintendo way back in 1981.
This is the game that got Nintendo started in America (it wasn't their first American game, just their first hit). Designed by the legendary Shigeru Miyamoto, this game was basically designed to fill a bunch of leftover cabinets that they had made for the game Radar Scope (which flopped big time). This replacement game went on to shape Nintendo's entire future product line, and inspired well over a dozen sequels, and Mario (the hero of the game), has gone on to star in his own series of games.
Rumor has it that the original title to this game was supposed to be "Monkey Kong". The story says that a hastily scribbled note (or fax), caused thousands of sets of Donkey Kong graphics (marquees, sideart. etc) to be created (instead of the correct title). It is said that they simply decided to change the game's name, rather than wait for the correct graphics. This rumor isn't true (or at least Nintendo denies it), but it is interesting nonetheless.
This game had a guest appearance on Mister Rogers' Neighborhood, where a young boy attempted to explain the game to Mr. Rogers (although the whole thing seemed like a cheap attempt to somehow be associated with a popular trend).
In this game you play the part of Mario (in his first appearance, although back then they were still calling him "Jumpman"). The object is to climb to the top of a series of towers and girders to save your girlfriend "Pauline", who later became well known as "Princess Toadstool" or "Peach" in Japan (noder Milen says that the characters of Pauline and Peach are unrelated, which is possibly true, sources vary on this).
Play is controlled with a 4-Way joystick and a single button. You move Mario around in his attempt to save Pauline, while avoiding the barrels, fireballs, and other dangers. You can move up and down ladders as well, while certain areas of the board will drop away after you walk over them. You can increase your score by collecting umbrellas, hats, purses and other bonus items that are scattered around some of the levels. The only weapon at your disposal is a hammer that you can grab, and use to smash enemies for a short amount of time (although you cannot climb ladders while wielding the hammer, limiting its use somewhat).
There are four different levels to the game. The Girder, Elevator and Conveyor Belt levels cab be beaten simply by touching "Pauline" (who will be at the top of the screen, near "Donkey Kong" himself). Walking over all the visible rivets on the board beats the rivet level. Many of the levels will repeat themselves several times (especially the girder and rivet levels), before you finally see all of the levels.
On early versions of this game (any machine that displays "Nintendo" instead of "Nintendo of America" on the copyright screen, most of these machines will be red instead of blue), you could go up to the top of any ladder and sit there indefinitely without being hit by a rolling barrel. To do this you simply had to move Mario's hands to just over the top of the ladder. Any barrels will then roll over his hands without incident, and no barrels will come rolling down the ladder at all. (I myself prefer this version of the game, under MAME you can play this version by selecting the "Japan Set 2" romset for Donkey Kong).
Donkey Kong machines came in one of four different cabinets. Two flavors of upright machines, plus a cabaret, and a cocktail thrown in for good measure. The cocktails and cabarets will mostly black and woodgrain, and were not excessively decorated. But the upright versions were.
The red upright versions are actually Radarscope cabinets that have been factory converted to Donkey Kong. These are fairly rare (even though they were supposed to be the only Donkey Kong machines), and feature slightly different gameplay. The blue uprights (which are the most common), are a very rectangular affair, with quite a lot of artwork. They have orange-ish sticker style sideart (with Mario and Kong on them), with control panel, marquee, and monitor bezel graphics to match.
This game does not use a standard arcade monitor. It requires a "Nintendo Compatible" monitor (a normal monitor will display the picture like that of a photographic negative). This simple little monitor change basically launched the entire Nintendo Vs. Unisystem later on. Because only Donkey Kong series games and Vs. titles would work on these monitors (forcing operators to buy conversion kits for those games instead of a competitors game).
Where to play
You can play Donkey Kong on just about any game console. The Super Game Boy, and ColecoVision ports were especially good, and Donkey Kong 64 even includes a version of this game in one of the bonus rounds. Or you can play one of many clones of this game that have been released for PC hardware (you can even download MAME to play the original version). There is even a 2 panel LCD Game&Watch version. This game is common enough that you may actually encounter a real machine out in the wild from time to time (my last sighting of one was in 1999).
This game is very popular, but it may not be the best title to add this to your arcade game collection. The reason I suggest against it is because the game is very repetitive, and you may quickly grow tired of that $900 Donkey Kong machine that seemed so fun when you first brought it home. There is one good point to owning a Donkey Kong. That is the fact that all the parts to this game are available as reproductions (you can even purchase rebuilt boardsets and monitors from several sources. This means that you can pretty much build (or restore) a Donkey Kong from almost nothing, without even leaving your house (you will still need a Nintendo arcade cabinet to install everything in, but these are easy to find).
Your Donkey Kong cabinet will easily convert to Donkey Kong Junior, Donkey Kong 3 or any Nintendo Vs. Unisystem title. You will only need the PCB boards for the new title, (and an 8-Way joystick in the case of Vs. titles). Just be sure and convert it back if you ever wish to sell it.