Yoshi's Story is a tech demo erected to show off the capabilities of the Game Boy Advance, originally shown in 2000. It was modeled heavily after the Nintendo 64 video game Yoshi's Story, featuring nearly identical graphics and gameplay. In the tech demo, the player controls a green Yoshi and navigates through a stage, defeating typical Mario enemies such as Bullet Bills, Shy Guys, and Bob-ombs. Like in Yoshi's Story, the color of the Shy Guy would change when Yoshi performed a ground pound. There were also super-sized Shy Guys that would shrink when stomped on.
Before the tech demo started, the player would see Yoshi's Island rotate, showing off the abilities of the GBA's.AMI FMV. It was reported that the game was just a tech demo though some speculated that Nintendo would create a full game as they did with the "tech demo" of Super Mario Bros. on the Game Boy Color.
Despite not being released as a retail game, Yoshi's Story was important because of two reasons:
It was among the first games shown for the Game Boy Advance and showed off its technical abilities.
It was shipped with early development kits to developers to demonstrate what the Game Boy Advance could do.
Interestingly, in an early (and official),picture of the Game Boy Advance Yoshi's Story was the game that was being played, which led some to believe that it was actually going to be released. IGN went as far as to say that they expected the game to eventually release on the system. Instead of Yoshi's Story, the Game Boy Advance did receive Super Mario Advance 3: Yoshi's Island and Yoshi Topsy-Turvy.