Though I like Yellow a lot, I'm going to have another Pokemon game I loved more in the list, so I'm bumping it down as honorable mention. Because really it was the same game.
The success of the TV show had fans begging for it.
However in Red and Blue he looked like this.
So they then made him look like his anime counterpart. Some other little changes, but more or less another $30 bucks for the same game with some Pikachu paint.