Most gamers don't know this, but a lot of video games released in the US were something completely different in Japan. A few characters were changed and the games were localized for American consumption. A handful of these are pretty good games that were not hurt by the changes made to them, some actually benefited from the changes. Then there were a few that weren't good before, and they were still pretty bad after the tweaks made for the US market.
The two most well known of these are the also the two extremes of this practice. When Nintendo released Super Mario Bros. 2 for the Famicom, it was a tough game for Japanese players, so Nintendo figured the game would be too tough for American gamers. Nintendo decided to use a substitute game and call it Super Mario Bros. 2. Another game produced by Shigeru Miyamoto, Yume Kojo: Doki Doki Panic, was chosen. The main characters were swapped out for Mario, Luigi, Toad, and Princess Toadstool, a splash of the original Super Mario Bros. soundtrack was thrown in, and Mario's strangest adventure was released to the public. American gamers wouldn't know the truth until the release of Super Mario All Stars for the SNES.
Another well known case of the swap was Yo Noid. For some reason, the folks at Domino's Pizza wanted their mascot everywhere, and tapped Capcom to make a video game. The game was a modified version of a Famicom game called Kamen no Ninja Hanamaru. This was one of Capcom's worst games on the NES, and it wasn't because of the localization. It was a bad game in Japan as well, and as the old folks say: "Two wrongs don't make a right".
Another example of major changes during localization was Taito's Power Blade. The original game was known as Power Blazer, and it was honestly one of the most blatant Mega Man rip offs ever conceived. To avoid that dubious tag in the US, Taito completely reworked the bulk of the game, moving away from the cartoony look of the original and giving the US version much better control. The game was so well received upon it's US release that it appeared on the cover of Nintendo Power magazine in 1991.