Say "fuzzle pickles!" *SNAP*
Earthbound was developed by HAL Laboratories and Ape Studios and published by Nintendo for the SNES in April, 1994. (In Japan, it is known as Mother 2, and, obviously, it is the sequel to Mother, known as Earthbound Zero to American fans. More on this below.) As of this noding), the game is mildly uncommon, compounded by the RPG-fanatics demand running up the value. The game is especially desirable if the copy includes the Player's Guide originally packaged with the game. Of course, if you want to evade the expense and effort, the ROM, like most SNES games, is complete and emulates well. (A GBA compilation of this game and its prequel is has been released in Japan, with constant rumors of a US release.)
Earthbound is quite possibly the most bizarre RPG ever to be released in the United States, and retains a certain cult following even to this day. Rather than being a typical "Slay-the-Unspeakably-Evil-Dark-Master-and-collect-the-Widgets-Of-Power" quest, the unspeakable evil announces its presence with a meteorite curiously shaped exactly like a pizza, and attacks with hordes of zombies, spiteful crows, and 1950's robots. Why Giygas would want to conquer this planet is anybody's guess; the world seems to be filled with the Japanese idea of Americans, as drawn from '50s sitcoms and '60s B science fiction films, a twisted mix of Leave It To Beaver and The Day The Earth Stood Still.
The game doesn't just offer an amusingly twisted take on American culture. No, it parodies role-playing games too, from the avuncular mentor, a fly from outer space, who accidentally gets swatted, to the town names, like Onett, Twoson, and Threed. The game is inexplicably aggressive animals and passersby, silly status ailments like "stuffed up" and "sunstroke", hamburgers that refill your hit points (they're better with ketchup), yo-yos, baseball bats, and frying pans to subdue your foes, and insanely hilarious get-quests (to remove a giant pencil in your way, you need to go find...well, what else? A pencil eraser.)
The cast, ranging from the humorous to the simply inexplicable, is the highlight of this game. Whether it's the Runaway Five, a quintet oddly reminiscent of the Blues Brothers, or the Mr. Saturn, with their bizarre grammar and swirly hand-written font for text, or Ness's clueless parents and oddly clueful dog, even down to people who complain about their pants when you accoust them on the street, the people in this game have more personality than all the Final Fantasies combined.
Unfortunately, the game is not without flaws. The humor isn't 100% consistant, as many of the jokes are simply unfunny bathroom humor. Farts cease to be funny after about the third time. The battles are incredibly tedious, as 99.9% of them are "press A a bunch of times", and boss battles are "attack, attack, attack, heal, repeat." This is not a game to be played for the game, so much as a game to be played for the ambiance.
The game was a huge hit in Japan (released August 27, 1994 as Mother 2), and Nintendo expected similar performance in the US, leading off with a marketing blitz and shipping a Player's Guide in the box with the game. Not only that, but a truly professional job of translation was given to this game, a rare treat in RPGs of the era. Sadly, Nintendo made three key mistakes. Firstly, part of what made Mother 2 such a hit was the fact that it was the sequel to a successful RPG (one which almost made it to the US; see Earthbound Zero). Secondly, RPGs were not yet a mainstream genre in the US, and wouldn't be until after Final Fantasy VII. Lastly, the sales it would've had from the RPG hardcore were diluted by the aging graphics, juvenile theme, and the general low challenge of the game.
Why would you want to play this game? Simple. It's probably one of the funniest console games ever.
Why wouldn't you? Well, the game itself is just in the way of the ambiance. The combat is boring, levelling up is boring, and the quests are intentionally pointless, parodies of the get-quests of other RPGs.
This game is the sequel to a game that almost came to the US, known now as Earthbound Zero. There's been an abortive attempt to make a sequel for the N64/64DD (Earthbound 64/Mother 3), although there's talk of reviving the scenario for this game and putting Mother 3 on the Game Boy Advance. And, of course, Ness and a number of the Earthbound places and items made it into Super Smash Brothers and Super Smash Bros. Melee.
Sources: The unending vat of knowledge that is GameFAQs, starmen.net